U.S. patent application number 11/988232 was filed with the patent office on 2009-03-26 for refrigerating apparatus.
This patent application is currently assigned to DAIKIN INDUSTRIES, LTD.. Invention is credited to Azuma Kondo, Masaaki Takegami, Kenji Tanimoto.
Application Number | 20090077985 11/988232 |
Document ID | / |
Family ID | 37757546 |
Filed Date | 2009-03-26 |
United States Patent
Application |
20090077985 |
Kind Code |
A1 |
Takegami; Masaaki ; et
al. |
March 26, 2009 |
Refrigerating Apparatus
Abstract
A refrigerant return mechanism (5) is provided for returning
liquid refrigerant in a receiver (17) to a circulation path.
Whereby, the liquid refrigerant in the receiver (17) is forcedly
returned to the circulation path in an operation state where the
circulation path is formed in which the refrigerant sent out from
compression mechanism (11D, 11E) flows from a second user side unit
(20) to first user side units (30, 40) and is then returned to the
compression mechanisms (11D, 11E).
Inventors: |
Takegami; Masaaki; (Osaka,
JP) ; Kondo; Azuma; (Osaka, JP) ; Tanimoto;
Kenji; (Osaka, JP) |
Correspondence
Address: |
BIRCH STEWART KOLASCH & BIRCH
PO BOX 747
FALLS CHURCH
VA
22040-0747
US
|
Assignee: |
DAIKIN INDUSTRIES, LTD.
Osaka
JP
|
Family ID: |
37757546 |
Appl. No.: |
11/988232 |
Filed: |
August 11, 2006 |
PCT Filed: |
August 11, 2006 |
PCT NO: |
PCT/JP2006/315914 |
371 Date: |
January 3, 2008 |
Current U.S.
Class: |
62/175 ;
62/498 |
Current CPC
Class: |
F25B 2313/02741
20130101; F25B 13/00 20130101; F25B 2313/023 20130101; F25B
2313/02732 20130101; F25B 2400/22 20130101; F25B 2500/07 20130101;
F25B 2700/21152 20130101; F25B 2313/007 20130101; F25B 1/10
20130101; F25B 2400/16 20130101; F25B 2500/24 20130101; F25B
2500/31 20130101; F25B 2400/0751 20130101 |
Class at
Publication: |
62/175 ;
62/498 |
International
Class: |
F25B 7/00 20060101
F25B007/00; F25B 1/00 20060101 F25B001/00 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 15, 2005 |
JP |
2005-235447 |
Dec 28, 2005 |
JP |
2005-377703 |
Claims
1. A refrigerating apparatus comprising: a heat source side unit
(10) including a compression mechanism (11D, 11E), a heat source
side heat exchanger (15), and a receiver (17); a first user side
unit (30, 40) including a first user side heat exchanger (31, 41);
a second user side unit (20) including a second user side heat
exchanger (21); and gas side communication pipes (51, 52) and
liquid side communication pipes (53, 54, 55) which connect each
unit (10, 20, 30, 40) to form a refrigerant circuit (50), the gas
side communication pipes (51, 52) including a first gas side
communication pipe (51) connected to the heat source side unit (10)
and the first user side unit (30, 40) and a second gas side
communication pipe (53) connected to the heat source side unit (10)
and the second user side unit (20), and the liquid side
communication pipes (53, 54, 55) including a collection liquid pipe
(53) connected to the heat source side unit (10), a first branch
liquid pipe (54) branching from the collection liquid pipe (53) and
connected to the first user side unit (30, 40), and a second branch
liquid pipe (55) branching from the collection liquid pipe (53) and
connected to the second user side unit (20), wherein the
refrigerant circuit (50) is capable of forming a refrigerant
circulation path in which refrigerant sent out from the compression
mechanisms (11D, 11E) flows from the second user side unit (20) to
the first user side unit (30, 40) and is then returned to the
compression mechanism (11D, 11E), and a refrigerant return
mechanism (5) is provided for returning liquid refrigerant in the
receiver (17) to the circulation path.
2. The refrigerating apparatus of claim 1, wherein the refrigerant
return mechanism (5) includes an introduction pipe (71) for
introducing high-pressure refrigerant discharged from the
compression mechanism (11D, 11E) into the receiver (17), and the
liquid refrigerant in the receiver (17) is returned to the
circulation path through the collection liquid pipe (53) in such a
manner that the high-pressure refrigerant from the introduction
pipe (71) is introduced into the receiver (17) to increase an inner
pressure of the receiver (17).
3. The refrigerating apparatus of claim 1, wherein the refrigerant
return mechanism (5) includes a communication pipe (67) for
allowing the receiver (17) to communicate with a suction side of
the compression mechanism (11D, 11E), and the liquid refrigerant in
the receiver (17) is returned to the circulation path in such a
manner that the compression mechanism (11D, 11E) sucks the liquid
refrigerant through the communication pipe (67).
4. The refrigerating apparatus of claim 1, wherein the refrigerant
return mechanism (5) includes a communication mechanism (13) for
allowing the receiver (17) to communicate with a discharge side of
the compression mechanism (11D, 11E) through the heat source side
heat exchanger (15), and the liquid refrigerant in the receiver
(17) is returned to the circulation path through the collection
liquid pipe (53) in such a manner that the communication mechanism
(13) allows the receiver (17) to communicate with the discharge
side of the compression mechanism (11D, 11E) to cause high-pressure
refrigerant discharged from the compression mechanism (11D, 11E) to
flow into the receiver (17).
5. The refrigerating apparatus of any one of claims 1 to 4, further
comprising: suction side superheat detection means (79, 81) for
detecting a degree of superheat of refrigerant flowing from the
first user side heat exchanger (31, 41) toward a suction side of
the compression mechanism (11D, 11E); and control means (95) for
controlling the refrigerant return mechanism (5) so that the
refrigerant in the receiver (17) is returned to the circulation
path when a detection value of the suction side superheat detection
means (79, 81) is equal to or larger than a predetermined
value.
6. The refrigerating apparatus of any one of claims 1 to 4, further
comprising: discharge side superheat detection means (75, 76) for
detecting a degree of superheat of refrigerant discharged from the
compression mechanism (11D, 11E); and control means (95) for
controlling the refrigerant return mechanism (5) so that the
refrigerant in the receiver (17) is returned to the circulation
path when a detection value of the discharge side superheat
detection means (75, 76) is equal to or larger than a predetermined
value.
7. The refrigerating apparatus of any one of claims 1 to 4, further
comprising: discharge side refrigerant temperature detection means
(76) for detecting a temperature of refrigerant discharged from the
compression mechanism (11D, 11E); and control means (95) for
controlling the refrigerant return mechanism (5) so that the
refrigerant in the receiver (17) is returned to the circulation
path when a detection value of the discharge side refrigerant
temperature detection means (76) is equal to or larger than a
predetermined value.
8. A refrigerating apparatus comprising: a heat source side unit
(10) including a compression mechanism (11D, 11E), a heat source
side heat exchanger (15), and a receiver (17); a first user side
unit (30, 40) including a first user side heat exchanger (31, 41);
a second user side unit (20) including a second user side heat
exchanger (21); and gas side communication pipes (51, 52) and
liquid side communication pipes (53, 54, 55) which connect each
unit (10, 20, 30, 40) to form a refrigerant circuit (50), the gas
side communication pipes (51, 52) including a first gas side
communication pipe (51) connected to the heat source side unit (10)
and the first user side unit (30, 40) and a second gas side
communication pipe (53) connected to the heat source side unit (10)
and the second user side unit (20), and the liquid side
communication pipes (53, 54, 55) including a collection liquid pipe
(53) connected to the heat source side unit (10), a first branch
liquid pipe (54) branching from the collection liquid pipe (53) and
connected to the first user side unit (30, 40), and a second branch
liquid pipe (55) branching from the collection liquid pipe (53) and
connected to the second user side unit (20), wherein the
refrigerant circuit (50) includes a switching mechanism (12) which
switches between a first operation mode and a second operation
mode, the first operation mode being a mode in which refrigerant
sent out from the compression mechanism (11D, 11E) flows from the
second user side unit (20) to the first user side unit (30, 40) and
is then returned to the compression mechanism (11D, 11E), and the
second operation mode being a mode in which the refrigerant sent
out from the compression mechanism (11D, 11E) flows from the heat
source side heat exchanger (15) into the receive (17) and into the
first user side unit (30, 40) and is then returned to the
compression mechanism (11D, 11E), and the liquid refrigerant
retained in the receiver (17) in the first operation mode is
returned to the first user side unit (30, 40) through the
collection liquid pipe (53) by switching the switching mechanism
(12) from the first operation mode to the second operation mode.
Description
TECHNICAL FIELD
[0001] The present invention relates to refrigerating apparatuses
and particularly relates to a refrigerating apparatus including a
plurality of user side heat exchangers for refrigeration/freezing
and air conditioning capable of performing a 100% heat recovery
operation therebetween.
BACKGROUND ART
[0002] Conventionally, refrigerating apparatuses performing a
refrigeration cycle have been known. The refrigerating apparatuses
are widely utilized as air conditioners for cooling/heating indoors
and coolers, such as showcases for refrigerating, or freezing food
and the like. Of the refrigerating apparatuses, some perform both
air conditioning and refrigeration/freezing (see Patent Document 1,
for example). Installation of only a single refrigerating apparatus
of this type in, for example, a convenience store attains indoor
air conditioning and cooling of showcases and the like.
[0003] In the above refrigerating apparatus, a plurality of user
side heat exchangers (refrigerating and freezing heat exchangers,
an air conditioning heat exchanger, and the like) provided in user
side units, such as refrigerating and frozen showcases, an air
conditioning indoor unit, and the like are connected in parallel to
a heat source side heat exchanger (an outdoor heat exchanger) of a
heat source side unit (an outdoor unit) installed outdoors through
liquid side communication pipes and gas side communication
pipes.
[0004] Herein, in the case where a refrigerant circuit includes two
system circuits of a first system circuit for
refrigeration/freezing and a second system circuit for air
conditioning, two communication pipes are used for each of a liquid
line and a gas line in general. While in some refrigerating
apparatuses, the two system circuits share one liquid side
communication pipe to reduce the number of communication pipes (see
Patent Document 2).
[0005] Specifically, the refrigerant circuit of this apparatus is
composed as shown in FIG. 13. In the drawing, reference numeral
(101) denotes an outdoor unit, (102) denotes an indoor unit, (103)
denotes a refrigerated showcase (a refrigerating unit), and (104)
denotes a frozen showcase (a freezing unit). The outdoor unit (101)
includes compression mechanisms (105, 106), an outdoor heat
exchanger (107), an outdoor expansion valve (108), and a receiver
(109), while the indoor unit (102) includes an indoor heat
exchanger (an air conditioning heat exchanger) (110) and an indoor
expansion valve (111). The refrigerated showcase (103) includes a
refrigerating heat exchanger (112) and a refrigerating expansion
valve (113) while the frozen showcase (104) includes a freezing
heat exchanger (114), a freezing expansion valve (115), and a
booster compressor (116).
[0006] The refrigerant circuit (120) of this refrigerating
apparatus includes a first system circuit for
refrigeration/freezing and a second system circuit for air
conditioning, wherein the first system circuit is so composed to
circulate refrigerant in one direction between the outdoor heat
exchanger (107) and the refrigerating and freezing heat exchangers
(112, 114) while the second system circuit is so composed that the
refrigerant circulates in two directions between the outdoor heat
exchanger (107) and the indoor heat exchanger (110). The system
circuits share a single liquid side communication pipe (121) as a
liquid line for both the system circuits.
[0007] In addition to indoor air conditioning and cooling of each
showcase with the use of the outdoor heat exchanger (107) installed
outdoor as a heat source, the refrigerating apparatus can perform,
heating and refrigeration/freezing at 100% heat recovery using the
indoor heat exchanger (110) as a condenser and the refrigerating
and freezing heat exchangers (112, 114) as evaporators without
using the outdoor heat exchanger (107). When the 100% heat recovery
operation is performed in the refrigerant circuit (120) using the
single liquid side communication pipe (121), a refrigerant
circulation path is formed in the refrigerant circuit (120) in
which the refrigerant discharged from the compression mechanisms
(105, 106) is condensed in the indoor heat exchanger (110),
evaporates in the refrigerating and freezing heat exchangers (112,
114), and is then returned again to the compression mechanisms
(105, 106). In other words, in performing the 100% heat recovery
operation, the liquid refrigerant condensed in the indoor heat
exchanger (110) is introduced into the refrigerating and freezing
heat exchangers (112, 114) without allowing it to flow from the
receiver (109) into the heat source side heat exchanger (107).
[0008] For example, when the outdoor air temperature is low,
however, the pressure in the receiver (109) lowers to lower the
inner pressure of the liquid side communication pipe (121), so that
the liquid refrigerant flowing out from the indoor heat exchanger
(110) is liable to flow into the receiver (109) through the liquid
side communication pipe (121). This invites shortage of the
refrigerant flowing in the refrigerating and freezing heat
exchangers (112, 114). When the refrigerant flowing in the
refrigerating and freezing heat exchangers (112, 114) is short, the
cooling capacity for cooling each inside of the showcases (103,
104) lowers.
[0009] To tackling this problem, a relief valve (117) is provided
in the middle of the refrigerant path from the liquid side
communication pipe (121) to the receiver (109). Though the relief
valve (117) opens when the refrigerant pressure in the liquid side
communication pipe (121) is increased to be equal to or higher than
a predetermined value, it is closed until the pressure reaches the
predetermined value. When the operation pressure of the relief
valve (117) is set at a pressure higher than the pressure of the
liquid side communication pipe (121) at the 100% heat recovery
operation, the liquid refrigerant is prevented from flowing into
the receiver (109) in the 100% heat recovery operation. Further,
even when the outdoor air temperature is low, the refrigerant flow
in the refrigerant circuit (120) can be stabilized to prevent the
freezing capacity from lowering.
[0010] The above refrigerating apparatus can perform a heating
operation of the refrigeration cycle with the use of the outdoor
heat exchanger (107) as an evaporator. In this operation, however,
the relief valve (117) receives the suction pressure of the
compressor (106) to be opened. In a cooling operation, the
refrigerant does not flow in a path in which the relief valve (117)
is provided.
Patent Document 1: Japanese Patent Application Laid-Open
Publication No. 2001-280749
Patent Document 2: Japanese Patent Application Laid-Open
Publication No. 2005-134103
SUMMARY OF THE INVENTION
Problems that the Invention is to Solve
[0011] In the above apparatus, the refrigerant may not be prevented
completely from flowing into the receiver when the relief valve is
closed in some cases, namely, the cases where refrigerant leakage
occurs at the relief valve. In these cases, the refrigerant
gradually flows into the receiver, and less or no refrigerant
flowing therein flows out from the receiver during the 100% heat
recovery operation. Accordingly, the refrigerant in the receiver
increases while the refrigerant in the refrigerating and freezing
heat exchangers as the user side units is short. This lowers the
capacity of cooling each inside of the showcases. Such a problem
occurs in a case with a valve mechanism different from the relief
valve, for example, a solenoid valve, as well. In any valve
mechanisms, it is difficult to prevent refrigerant leakage
completely when comparatively high-pressure refrigerant works.
[0012] Even in the case where the refrigerant should be prevented
from flowing into the receiver, the refrigerant pressure working on
the relief valve may be increased excessively to open the relief
valve. In this case, also, excessive refrigerant flowing in the
receiver causes refrigerant shortage similarly to the foregoing to
lower the capacity of cooling each inside of the showcases.
[0013] The present invention has been made in view of the foregoing
and has its object of preventing, in a refrigerating apparatus
which includes a plurality of system user side heat exchangers and
in which a plurality of liquid lines share a single liquid side
communication pipe, refrigerant shortage in a user side unit which
is caused due to an increase in refrigerant in a receiver.
Means for Solving the Problems
[0014] A first aspect of the present invention is directed to a
refrigerating apparatus including: a heat source side unit (10)
including a compression mechanism (11D, 11E), a heat source side
heat exchanger (15), and a receiver (17); a first user side unit
(30, 40) including a first user side heat exchanger (31, 41); a
second user side unit (20) including a second user side heat
exchanger (21); and gas side communication pipes (51, 52) and
liquid side communication pipes (53, 54, 55) which connect each
unit (10, 20, 30, 40) to form a refrigerant circuit (50), the gas
side communication pipes (51, 52) including a first gas side
communication pipe (51) connected to the heat source side unit (10)
and the first user side unit (30, 40) and a second gas side
communication pipe (53) connected to the heat source side unit (10)
and the second user side unit (20), and the liquid side
communication pipes (53, 54, 55) including a collection liquid pipe
(53) connected to the heat source side unit (10), a first branch
liquid pipe (54) branching from the collection liquid pipe (53) and
connected to the first user side unit (30, 40), and a second branch
liquid pipe (55) branching from the collection liquid pipe (53) and
connected to the second user side unit (20). Wherein the
refrigerant circuit (50) is capable of forming a refrigerant
circulation path in which refrigerant sent out from the compression
mechanisms (11D, 11E) flows from the second user side unit (20) to
the first user side unit (30, 40) and is then returned to the
compression mechanism (11D, 11E), and a refrigerant return
mechanism (5) is provided for returning liquid refrigerant in the
receiver (17) to the circulation path.
[0015] Referring to a second aspect of the present invention, in
the first aspect, the refrigerant return mechanism (5) includes an
introduction pipe (71) for introducing high-pressure refrigerant
discharged from the compression mechanism (11D, 11E) into the
receiver (17), and the liquid refrigerant in the receiver (17) is
returned to the circulation path through the collection liquid pipe
(53) in such a manner that the high-pressure refrigerant from the
introduction pipe (71) is introduced into the receiver (17) to
increase an inner pressure of the receiver (17).
[0016] Referring to a third aspect of the present invention, in the
first aspect, the refrigerant return mechanism (5) includes a
communication pipe (67) for allowing the receiver (17) to
communicate with a suction side of the compression mechanism (11D,
11E), and the liquid refrigerant in the receiver (17) is returned
to the circulation path in such a manner that the compression
mechanism (11D, 11E) sucks the liquid refrigerant through the
communication pipe (67).
[0017] Referring to a fourth aspect of the present invention, in
the first aspect, the refrigerant return mechanism (5) includes a
communication mechanism (13) for allowing the receiver (17) to
communicate with a discharge side of the compression mechanism
(11D, 11E) through the heat source side heat exchanger (15), and
the liquid refrigerant in the receiver (17) is returned to the
circulation path through the collection liquid pipe (53) in such a
manner that the communication mechanism (13) allows the receiver
(17) to communicate with the discharge side of the compression
mechanism (11D, 11E) to cause high-pressure refrigerant discharged
from the compression mechanism (11D, 11E) to flow into the receiver
(17).
[0018] Referring to a fifth aspect of the present invention, the
refrigerating apparatus in any one of the first to fourth aspects
further includes: suction side superheat detection means (79, 81)
for detecting a degree of superheat of refrigerant flowing from the
first user side heat exchanger (31, 41) toward a suction side of
the compression mechanism (11D, 11E); and control means (95) for
controlling the refrigerant return mechanism (5) so that the
refrigerant in the receiver (17) is returned to the circulation
path when a detection value of the suction side superheat detection
means (79, 81) is equal to or larger than a predetermined
value.
[0019] Referring to a sixth aspect of the present invention, the
refrigerating apparatus in any one of the first to fourth aspects
further includes: discharge side superheat detection means (75, 76)
for detecting a degree of superheat of refrigerant discharged from
the compression mechanism (11D, 11E); and control means (95) for
controlling the refrigerant return mechanism (5) so that the
refrigerant in the receiver (17) is returned to the circulation
path when a detection value of the discharge side superheat
detection means (75, 76) is equal to or larger than a predetermined
value.
[0020] Referring to a seventh aspect of the present invention, the
refrigerating apparatus in any one of first to fourth aspect
further includes: discharge side refrigerant temperature detection
means (76) for detecting a temperature of refrigerant discharged
from the compression mechanism (11D, 11E); and control means (95)
for controlling the refrigerant return mechanism (5) so that the
refrigerant in the receiver (17) is returned to the circulation
path when a detection value of the discharge side refrigerant
temperature detection means (76) is equal to or larger than a
predetermined value. An eight aspect of the present invention is
directed to a refrigerating apparatus including: a heat source side
unit (10) including a compression mechanism (11D, 11E), a heat
source side heat exchanger (15), and a receiver (17); a first user
side unit (30, 40) including a first user side heat exchanger (31,
41); a second user side unit (20) including a second user side heat
exchanger (21); and gas side communication pipes (51, 52) and
liquid side communication pipes (53, 54, 55) which connect each
unit (10, 20, 30, 40) to form a refrigerant circuit (50), the gas
side communication pipes (51, 52) including a first gas side
communication pipe (51) connected to the heat source side unit (10)
and the first user side unit (30, 40) and a second gas side
communication pipe (53) connected to the heat source side unit (10)
and the second user side unit (20), and the liquid side
communication pipes (53, 54, 55) including a collection liquid pipe
(53) connected to the heat source side unit (10), a first branch
liquid pipe (54) branching from the collection liquid pipe (53) and
connected to the first user side unit (30, 40), and a second branch
liquid pipe (55) branching from the collection liquid pipe (53) and
connected to the second user side unit (20). Wherein, the
refrigerant circuit (50) includes a switching mechanism (12) which
switches between a first operation mode and a second operation
mode, the first operation mode being a mode in which refrigerant
sent out from the compression mechanism (11D, 11E) flows from the
second user side unit (20) to the first user side unit (30, 40) and
is then returned to the compression mechanism (11D, 11E), and the
second operation mode being a mode in which the refrigerant sent
out from the compression mechanism (11D, 11E) flows from the heat
source side heat exchanger (15) into the receive (17) and into the
first user side unit (30, 40) and is then returned to the
compression mechanism (11D, 11E), and the liquid refrigerant
retained in the receiver (17) in the first operation mode is
returned to the first user side unit (30, 40) through the
collection liquid pipe (53) by switching the switching mechanism
(12) from the first operation mode to the second operation
mode.
[0021] --Operation--
[0022] In the first aspect of the present invention, in an
operation state where the circulation path is formed in which the
refrigerant sent out from the compression mechanism (11D, 11E)
flows from the second user side unit (20) to the first user side
unit (30, 40) and is then returned to the compression mechanism
(11D, 11E), the liquid refrigerant in the receiver (17) can be
forcedly returned to the circulation path by the refrigerant return
mechanism (5). In some cases, as described above, the refrigerant
will flow into the receiver (17) even through the refrigerant is
inhibited from flowing into the receiver (17), thereby reducing the
refrigerant in the circulation path. In the first aspect, however,
the refrigerant return mechanism (5) returns the liquid refrigerant
in the receiver (17) to the circulation path.
[0023] In the second aspect of the present invention, when the
liquid refrigerant in the receiver (17) is returned to the
circulation path, the high-pressure gas refrigerant discharged from
the compression mechanism (11D, 11E) is introduced into the
receiver (17) through the introduction pipe (71). When the
high-pressure gas refrigerant is introduced, the inner pressure of
the receiver (17) increases to push out the liquid refrigerant
therein, so that the liquid refrigerant thus pushed out from the
receiver (17) is returned to the circulation path through the
collection liquid pipe (53). This increases the rate of the gas
refrigerant having a small density while decreasing the rate of the
liquid refrigerant having a large density. As a result, the
refrigerant in the receiver (17) decreases while increasing the
refrigerant in the circulation path.
[0024] In the third aspect of the present invention, when the
liquid refrigerant in the receiver (17) is returned to the
circulation path, the communication pipe (67) allows the receiver
(17) to communicate with the suction side of the compression
mechanism (11D, 11E). When the receiver (17) communicates with the
suction side of the compression mechanism (11D, 11E), the liquid
refrigerant therein is sucked into the compression mechanism (11D,
11E) to return the liquid refrigerant in the receiver (17) forcedly
to the circulation path. This decreases the refrigerant in the
receiver (17) while increasing the refrigerant in the circulation
path.
[0025] In the fourth aspect of the present invention, when the
liquid refrigerant in the receiver (17) is returned to the
circulation path, the communication mechanism (13) allows the
receiver (17) to communicate with the discharge side of the
compression mechanism (11D, 11E) through the heat source side heat
exchanger (15) to cause the high-pressure refrigerant discharged
from the compression mechanism (11D, 11E) to flow into the receiver
(17). When the high-pressure gas refrigerant flows into the
receiver (17), the inner pressure of the receiver (17) increases to
push out the liquid refrigerant therein, similarly to the second
aspect. The liquid refrigerant pushed out from the receiver (17) is
returned to the circulation path through the collection liquid pipe
(53). This decrease the refrigerant in the receiver (17) while
increasing the refrigerant in the circulation path.
[0026] Further, the high-pressure gas refrigerant discharged from
the compression mechanism (11D, 11E) is introduced into the
receiver (17) via the heat source side heat exchanger (15). In the
fourth aspect, the heat source side heat exchanger (15) is utilized
as a flow path for introducing the high-pressure gas refrigerant
discharged from the compression mechanism (11D, 11E) into the
receiver (17). In the fifth aspect of the present invention, when
the degree of superheat of the refrigerant flowing from the first
user side heat exchanger (31, 41) to the suction side of the
compression mechanism (11D, 11E) is equal to or larger than the
predetermined value, the refrigerant return mechanism (5) returns
the liquid refrigerant in the receiver (17) to the circulation
path. In the first user side heat exchanger (31, 41), the less the
flow rate of the refrigerant is, the more the region where the
refrigerant in a liquid-vapor two-phase state flows decreases and
the more the region where the single-phase gas refrigerant flows
expands. As a result, the degree of superheat of the refrigerant
flowing out from the first user side heat exchanger (31, 41)
increases. In other words, the degree of superheat of the
refrigerant flowing out from the first user side heat exchanger
(31, 41) reflects the flow rate of the refrigerant flowing in the
first user side heat exchanger (31, 41). Accordingly, with the use
of the detection value of the suction side superheat detection
means (79, 81), appropriate judgment can be performed as to whether
or not the refrigerant is short in the first user side heat
exchanger (31, 41).
[0027] In the sixth aspect of the present invention, when the
degree of superheat of the refrigerant discharged from the
compression mechanism (11D, 11E) is equal to or larger than the
predetermined value, the refrigerant return mechanism (5) returns
the liquid refrigerant in the receiver (17) to the circulation
path. As described above, the less the flow rate of the refrigerant
in the first user side heat exchanger (31, 41) is, the more the
degree of superheat of the refrigerant flowing out from the first
user side heat exchanger (31, 41) and sucked to the compression
mechanism (11D, 11E) increases. Further, the larger the degree of
superheat of the refrigerant sucked to the compression mechanism
(31, 41) is, the larger the degree of superheat of the refrigerant
discharged from the compression mechanism (31, 41) is. In other
words, since the degree of superheat of the refrigerant discharged
from the compression mechanism (11D, 11E) reflects the flow rate of
the refrigerant in the first user side heat exchanger (31, 41),
appropriate judgment can be performed with the use of the detection
value of the discharge side superheat detection means (75, 76) as
to whether or not the refrigerant is short in the first user side
heat exchanger (31, 41).
[0028] In the seventh aspect of the present invention, when the
temperature of the refrigerant discharged from the compression
mechanism (11D, 11D) is equal to or higher than the predetermined
temperature, the refrigerant return mechanism (5) returns the
refrigerant in the receiver (17) to the circulation path. As
described above, the less the flow rate of the refrigerant in the
first user side heat exchanger (31, 41) is, the larger the degree
of superheat of the refrigerant discharged from the compression
mechanism (11D, 11E) becomes. The larger degree of superheat of the
refrigerant means high temperature thereof. Namely, the temperature
of the refrigerant discharged from the compression mechanism (11D,
11E) reflects the flow rate of the refrigerant in the first user
side heat exchanger (31, 41), and accordingly, appropriate judgment
can be performed with the use of the detection value of the
discharge side temperature detection means (76) as to whether or
not the refrigerant is short in the first user side heat exchanger
(31, 41).
[0029] In the eighth aspect of the present invention, when the
liquid refrigerant is retained much in the receiver (17) in the
first operation mode, the switching mechanism (12) switches the
operation mode from the first operation mode to the second
operation mode. In the second operation mode, similarly to the
fourth aspect, the high-pressure gas refrigerant discharged from
the compression mechanism (11D, 11E) flows into the receiver (17)
to increase the inner pressure thereof, thereby pushing out the
liquid refrigerant retained in the first operation mode. Then, the
liquid refrigerant pushed out from the receiver (17) is returned to
the first user side unit (30, 40) through the collection liquid
pipe (53).
EFFECTS OF THE INVENTION
[0030] In the present invention, in the operation state where the
circulate path in which the refrigerant decreases when the
refrigerant flows into the receiver (17) is formed, the refrigerant
return mechanism (5) returns the liquid refrigerant in the receiver
(17) to the circulation path. When the liquid refrigerant in the
receiver (17) is returned to the circulation path, the refrigerant
flowing in each user side unit (20, 30, 40) increases. Accordingly,
when the liquid refrigerant in the receiver (17) is returned to the
circulation path by the refrigerant return mechanism (5) before the
refrigerant is short in the user side units (20, 30, 40),
refrigerant shortage can be prevented in each user side unit (20,
30, 40) to avoid lowering of the capacity of temperature adjustment
in each user side unit (20, 30, 40).
[0031] In the third aspect of the present invention, during the
time when the liquid refrigerant in the receiver (17) is returned
to the circulation path, the compression mechanism (11D, 11E) sucks
the liquid refrigerant in the receiver (17) to lower the degree of
superheat on the suction side of the compression mechanism (11D,
11E). As a result, the refrigerant is returned to the circulation
path to obviate refrigerant shortage, and the degree of superheat
on the suction side is suppressed to reduce the required input of
the compression mechanism (11D, 11E).
[0032] In the fourth aspect of the present invention, the heat
source side heat exchanger (15) serving as an evaporator or a
condenser in the refrigeration cycle of the refrigerant circuit
(50) is utilized as a flow path for introducing the high-pressure
gas refrigerant discharged from the compression mechanism (11D,
11E) into the receiver (17). In other words, a part of the
refrigerating apparatus (1) is utilized as the refrigerant return
mechanism (5). This simplifies the refrigerating apparatus (1)
including the refrigerant return mechanism (5).
[0033] In the fifth aspect of the present invention, in view of the
fact that whether or not the refrigerant is short in the first user
side heat exchanger (31, 41) can be judged from the degree of
superheat of the refrigerant flowing from the first user side heat
exchanger (31, 41) to the suction side of the compression mechanism
(11D, 11E), the refrigerant return mechanism (5) is controlled on
the basis of the detection value of the suction side superheat
detection means (79, 81). Accordingly, the liquid refrigerant in
the receiver (17) can be returned to the circulation path at an
appropriate timing before the refrigerant is short in the first
user side heat exchanger (31, 41) to avoid the cooling capacity of
the first user side heat exchanger (31, 41) from lowering
definitely.
[0034] In the sixth aspect of the present invention, in view of the
fact that whether or not the refrigerant is short in the first user
side heat exchanger (31, 41) can be judged from the degree of
superheat of the refrigerant discharged from the compression
mechanism (11D, 11E), the refrigerant return mechanism (5) is
controlled on the basis of the detection value of the discharge
side superheat detection means (75, 76). Accordingly, the liquid
refrigerant in the receiver (17) can be returned to the circulation
path at an appropriate timing before the refrigerant is short in
the first user side heat exchanger (31, 41) to avoid the cooling
capacity of the first user side heat exchanger (31, 41) from
lowering definitely.
[0035] In the seventh aspect of the present invention, in view of
the fact that whether or not the refrigerant is short in the first
user side heat exchanger (31, 41) can be judged from the
temperature of the refrigerant discharged from the compression
mechanism (11D, 11E), the refrigerant return mechanism (5) is
controlled on the basis of the detection value of the discharge
side temperature detection means (76). Accordingly, the liquid
refrigerant in the receiver (17) can be returned to the circulation
path at an appropriate timing before the refrigerant is short in
the first user side heat exchanger (31, 41) to avoid the cooling
capacity of the first user side heat exchanger (31, 41) from
lowering definitely.
[0036] In the eighth aspect of the present invention, switching
from the first operation mode to the second operation mode causes
the liquid refrigerant retained in the receiver (17) in the first
operation mode to be returned to the first user side unit (30, 40).
Accordingly, in the eighth aspect, the refrigerant circulating
between the user side units (20, 30, 40) and the compression
mechanism (11D, 11E) is prevented from being short in the first
operation mode to avoid lowering of the capacity of temperature
adjustment in the user side units (20, 30, 40).
BRIEF DESCRIPTION OF THE DRAWINGS
[0037] FIG. 1 is diagram showing a refrigerant circuit of a
refrigerating apparatus in accordance with Embodiment 1 of the
present invention.
[0038] FIG. 2 is a diagram showing the refrigerant circuit in a
cooling operation in Embodiment 1.
[0039] FIG. 3 is a diagram showing the refrigerant circuit in a
freezing operation in Embodiment 1.
[0040] FIG. 4 is a diagram showing the refrigerant circuit in a
first cooling/freezing operation in Embodiment 1.
[0041] FIG. 5 is a diagram showing the refrigerant circuit in a
second cooling/freezing operation in Embodiment 1.
[0042] FIG. 6 is a diagram showing the refrigerant circuit in a
heating operation in Embodiment 1.
[0043] FIG. 7 is a diagram showing the refrigerant circuit in a
state where a solenoid valve of a hot gas bypass pipe is closed in
a first heating/freezing operation in Embodiment 1.
[0044] FIG. 8 is a diagram showing the refrigerant circuit in a
state where the solenoid valve of the hot gas bypass pipe is opened
in the first heating/freezing operation in Embodiment 1.
[0045] FIG. 9 is a diagram showing the refrigerant circuit in a
second heating/freezing operation in Embodiment 1.
[0046] FIG. 10 is a diagram showing the refrigerant circuit in a
third heating/freezing operation in Embodiment 1.
[0047] FIG. 11 is a diagram showing a refrigerant circuit of a
refrigerating apparatus in accordance with Embodiment 2 of the
present invention.
[0048] FIG. 12 is a diagram showing a refrigerant circuit of a
refrigerating apparatus in accordance with Embodiment 3 of the
present invention.
[0049] FIG. 13 is a diagram showing a refrigerant circuit of a
conventional refrigerating apparatus.
EXPLANATION OF REFERENCE NUMERALS
[0050] 1 refrigerating apparatus [0051] 5 refrigerant return
mechanism [0052] 10 outdoor unit (heat source side unit) [0053] 11D
compression mechanism [0054] 11E compression mechanism [0055] 13
second four-way switching valve (communication mechanism) [0056] 15
outdoor heat exchanger (heat source side heat exchanger) [0057] 17
receiver [0058] 20 indoor unit (second user side unit) [0059] 21
indoor heat exchanger (second user side heat exchanger) [0060] 30
refrigerating unit (first user side unit) [0061] 31 refrigerating
heat exchanger (first user side heat exchanger) [0062] 40 freezing
unit (first user side unit) [0063] 41 freezing heat exchanger
(first user side heat exchanger) [0064] 50 refrigerant circuit
[0065] 50A first system circuit [0066] 50B second system circuit
[0067] 51 first gas side communication pipe (gas side communication
pipe) [0068] 52 second gas side communication pipe (gas side
communication pipe) [0069] 53 collection liquid pipe (liquid side
communication pipe) [0070] 54 first branch liquid pipe (liquid side
communication pipe) [0071] 55 second branch liquid pipe (liquid
side communication pipe) [0072] 67 liquid injection pipe
(communication pipe) [0073] 71 hot gas bypass pipe (introduction
pipe) [0074] 75 high-pressure pressure sensor (discharge side
superheat detection means) [0075] 76 discharge side temperature
sensor (discharge side superheat detection means, discharge side
refrigerant temperature detection means) [0076] 79 low-pressure
pressure sensor (suction side superheat detection means) [0077] 81
suction side temperature sensor (suction side degree of superheat
detection means) [0078] 95 controller (control means)
BEST MODE FOR CARRYING OUT THE INVENTION
[0079] Embodiments of the present invention will be described below
in detail with reference to the accompanying drawings.
Embodiment 1
[0080] Embodiment 1 of the present invention will be described. A
refrigerant circuit of a refrigerating apparatus (1) in accordance
with Embodiment 1 is shown in FIG. 1. The refrigerating apparatus
(1) is installed in a convenience store and performs cooling of a
refrigerated showcase and a frozen showcase and cooling/heating of
the store.
[0081] The refrigerating apparatus (1) includes an outdoor unit (a
heat source side unit) (10), an indoor unit (a second user side
unit) (20), a refrigerating unit (a first user side unit) (30), and
a freezing unit (a first user side unit) (40). The units (10, 20,
30, 40) are connected to each other by means of gas side
communication pipes (51, 52) and liquid side communication pipes
(53, 54, 55) to form a refrigerant circuit (50) that performs a
vapor compression refrigeration cycle.
[0082] The gas side communication pipes (51, 52) are a first gas
side communication pipe (low-pressure gas pipe) (51) connected to
the outdoor unit (10), the refrigerating unit (30), and the
freezing unit (40) and a second gas side communication pipe (52)
connected to the outdoor unit (10) and the indoor unit (20). The
liquid side communication pipes (53, 54, 55) are a collection
liquid pipe (53) connected to the outdoor unit (10), a first branch
liquid pipe (54) branching from the collection liquid pipe (53) and
connected to the refrigerating unit (30) and the freezing unit
(40), and a second branch liquid pipe (55) branching from the
collection liquid pipe (53) and connected to the indoor unit (20).
The first branch liquid pipe (54) includes a refrigerating side
first branch liquid pipe (54a) on the refrigerating unit (30) side
and a freezing side first branch liquid pipe (54b) on the freezing
unit (40) side. In Embodiment 1, the indoor unit (20) and the
refrigerating and freezing units (30, 40) share the collection
liquid pipe (53), which is a part of the liquid side communication
pipes (53, 54, 55) on the outdoor unit (10) side, to form
three-pipe communication pipe structure.
[0083] The indoor unit (20) is switchable between a cooling
operation and a heating operation and is installed in a sales room,
for example. The refrigerating unit (30) is installed in the
refrigerated showcase to cool the air inside the showcase. The
freezing unit (40) is installed in the frozen showcase to cool the
air inside the showcase. Though the drawing shows only one indoor
unit (20), one refrigerating unit (30), and one freezing unit (40),
Embodiment 1 supposes that two indoor units (20) are connected in
parallel, eight refrigerating units (30) are connected in parallel,
and one freezing unit (40) is connected.
[0084] The refrigerant circuit (50) includes a
refrigerating/freezing first system side circuit (50A) which is
composed of the outdoor unit (10) as the heat source side unit and
the refrigerating unit (30) and the freezing unit (40) as the first
user side units and in which refrigerant circulates in one
direction and an air conditioning second system side circuit (50B)
which is composed of the outdoor unit (10) as the heat source side
unit and the indoor unit (20) as the second user side unit and in
which the refrigerant circulates in two directions.
[0085] <Outdoor Unit>
[0086] The outdoor unit (10) includes an inverter compressor (11A)
as a first compressor, a first non-inverter compressor (11B) as a
second compressor, a second non-inverter compressor (11C) as a
third compressor, a first four-way switching valve (12), a second
four-way switching valve (13), a third four-way switching valve
(14), and an indoor heat exchanger (51) as a heat source side heat
exchanger. The outdoor heat exchanger (15) is a fin and tube heat
exchanger of cross fin type, for example, and an outdoor fan (16)
as a heat source fan is provided in the vicinity thereof.
[0087] Each compressor (11A, 11B, 11C) is a hermetic high-pressure
dome type scroll compressor, for example. The inverter compressor
(11A) is a variable capacity compressor stepwisely or continuously
variable in capacity having a motor under inverter control. The
first non-inverter compressor (11B) and the second non-inverter
compressor (11C) are fixed capacity compressors each of which motor
drives at a given speed of rotation all the time.
[0088] The inverter compressor (11A), the first non-inverter
compressor (11B), and the second non-inverter compressor (11C)
compose compression mechanisms (11D, 11E) of the refrigerating
apparatus (1), wherein the compression mechanisms (11D, 11E) are a
first system compression mechanism (11D) and a second system
compression mechanism (11E). Specifically, the compression
mechanisms (11D, 11E) fall in either of two states in operation.
One is that: the inverter compressor (11A) and the first
non-inverter compressor (11B) serve as the first system compression
mechanism (11D) while the second non-inverter compressor (11C)
serves as the second system compression mechanism (11E). The other
one is that: the inverter compressor (11A) serves as the first
system compression mechanism (11D) while the first non-inverter
compressor (11B) and the second non-inverter compressor (11C) serve
as the second system compression mechanism (11E). In other words,
the inverter compressor (11A) is used for the
refrigerating/freezing first system side circuit (50A) fixedly
while the second non-inverter compressor (11C) is used for the air
conditioning second system side circuit (50B) fixedly, and the
first non-inverter compressor (11B) is used for the first system
side circuit (50A) and the second system side circuit (50B) by
switching.
[0089] Respective discharge pipes (56a, 56b, 56c) of the inverter
compressor (11A), the first non-inverter compressor (11B), and the
second non-inverter compressor (11C) are connected to one
high-pressure gas pipe (discharge pipe) (57). To the discharge pipe
(56b) of the first non-inverter compressor (11B) and the discharge
pipe (56c) of the second non-inverter compressor (11C), check
valves (CV1, CV2) are provided, respectively. The high-pressure gas
pipe (57) is connected to the first port (P1) of the first four-way
switching valve (12). The gas side end of the indoor heat exchanger
(15) is connected to the second port (P2) of the first four-way
switching valve (12) through an outdoor first gas pipe (58a). The
third port (P3) of the first four-way switching valve (12) is
connected to the second gas side communication pipe (52) through an
outdoor second gas pipe (58b). The fourth port (P4) of the first
four-way switching valve (12) is connected to the second four-way
switching valve (13).
[0090] The first port (P1) of the second four-way switching valve
(13) is connected to the discharge pipe (56c) of the second
non-inverter compressor (11C) through an auxiliary gas pipe (59).
The second port (P2) of the second four-way switching valve (13) is
a closed port. The third port (P3) of the second four-way switching
valve (13) is connected to the fourth port (P4) of the first
four-way switching valve (12) through a connection pipe (60). The
fourth port (P4) of the second four-way switching valve (13) is
connected to a suction pipe (61c) of the second non-inverter
compressor (11C). The second four-way switching valve (13) includes
the closed port as the second port (P2), and therefore, a three-way
switching valve may be replaced.
[0091] The first four-way switching valve (12) is switchable
between a first state indicated by the solid lines in FIG. 1 and a
second state indicated by the broken lines in FIG. 1, wherein the
first state is a state in which the first port (P1) communicates
with the second port (P2) while the third port (P3) communicates
with the fourth port (P4), and the second state is a state in which
the first port (P1) communicates with the third port (P3) while the
second port (P2) communicates with the fourth port (P4).
[0092] As well, the second four-way switching valve (13) is
switchable between a first state indicated by the solid lines in
FIG. 1 and a second state indicated by the broken lines in FIG. 1,
wherein the first state is a state in which the first port (P1)
communicates with the second port (P2) while the third port (P3)
communicates with the fourth port (P4), and the second state is a
state in which the first port (P1) communicates with the third port
(P3) while the second port (P2) communicates with the fourth port
(P4).
[0093] The liquid side end of the outdoor heat exchanger (15) is
connected to one end of an outdoor liquid pipe (62) as a liquid
line. In the middle of the outdoor liquid pie (62), a receiver (17)
is provided for storing liquid refrigerant. The other end of the
outdoor liquid pipe (62) is connected to the collection liquid pipe
(53) of the liquid side communication pipes (53, 54, 55).
[0094] The receiver (17) is connected to the heat source side heat
exchanger (15) and the liquid side communication pipes (53, 54, 55)
through a first inflow pipe (63a) allowing the refrigerant from the
heat source side heat exchanger (15) to flow thereinto, a first
outflow pipe (63b) allowing the refrigerant to flow out to the
liquid side communication pipes (53, 54, 55), a second inflow pipe
(63c) allowing the refrigerant from the liquid side communication
pipes (53, 54, 55) to flow thereinto, and a second outflow pipe
(63d) allowing the refrigerant to flow out to the outdoor heat
exchanger (15)
[0095] A suction pipe (61a) of the inverter compressor (11A) is
connected to the first gas side communication pipe (51) through a
low-pressure gas pipe (64) of the first system side circuit (50A).
A suction pipe (61c) of the second non-inverter compressor (11C) is
connected to a low-pressure gas pipe (an outdoor first gas pipe
(58a) or an outdoor second gas pipe (58b)) of the second system
side circuit (50B) via the first and second four-ways switching
valves (12, 13). A suction pipe (61b) of the first non-inverter
compressor (11B) is connected to the suction pipe (61a) of the
inverter compressor (11A) or the suction pipe (61c) of the second
non-inverter compressor (11C) via the third four-way switching
valve (14).
[0096] Specifically, a branch pipe (61d) is connected to the
suction pipe (61a) of the inverter compressor (11A), and a branch
pipe (61e) is connected to the suction pipe (61c) of the second
non-inverter compressor (11C). A branch pipe (61d) of the suction
pipe (61a) of the inverter compressor (11A) is connected to the
first port (P1) of the third four-way switching valve (14) via a
check valve (CV3); the suction pipe (61b) of the first non-inverter
compressor (11B) is connected to the second port (P2) of the third
four-way switching valve (14); and the branch pipe (61e) of the
suction pipe (61c) of the second non-inverter compressor (11C) is
connected to the third port (P3) of the third four-way switching
valve (14) via a check valve (CV4). The check valves (CV3, CV4)
respectively provided in the branch pipes (61d, 61e) allows the
refrigerant flowing toward the third four-way switching valve (14)
to flow while inhibiting the refrigerant from flowing in the
reverse direction. The fourth port (P4) of the third four-way
switching valve (14) is connected to a high-pressure introduction
pipe for introducing high pressure for the refrigerant circuit
(50), though not shown.
[0097] The third four-way switching valve (14) is switchable
between a first state indicated by the solid lines in FIG. 1 and a
second state indicated by the broken lines in FIG. 1, wherein the
first state is a state in which the first port (P1) communicates
with the second port (P2) while the third port (P3) communicates
with the fourth port (P4), and the second state is a state in which
the first port (P1) communicates with the fourth port (P4) while
the second port (P2) communicates with the third port (P3).
[0098] The first gas side communication pipe (51), the second gas
side communication pipe (52), and the collection liquid pipe (53)
of the liquid side communication pipes (53, 54, 55) extend from the
outdoor unit (10) to the outside, and closing valves (18a, 18b,
18c) are provided correspondingly thereto in the outdoor unit
(10).
[0099] To the outdoor liquid pipe (62), there are connected an
auxiliary liquid pipe (65) (the second outflow pipe (63d)) and a
liquid branch pipe (66) (the second inflow pipe (63c)) which bypass
the receiver (17). Refrigerant flows in the auxiliary liquid pipe
(65) mainly in a heating operation, and an outdoor expansion valve
(19) is provided therein as an expansion mechanism. The auxiliary
liquid pipe (65) is connected at one end thereof between the
outdoor heat exchanger (15) and the receiver (17) (in the first
inflow pipe (63a)) and is connected at the other end thereof
between the receiver (17) and the closing valve (18c). A check
valve (CV5) allowing only the refrigerant flowing toward the
receiver (17) to flow is provided between the receiver (17) and a
connection point of the outdoor liquid pipe (62) to the auxiliary
liquid pipe (65) which is located on the outdoor heat exchanger
(15) side.
[0100] The liquid branch pipe (66) is provided with, from the
closing valve (18c) side in this order, a check valve (CV6) and a
relief valve (117). The check valve (CV6) allows only the
refrigerant flowing from the closing valve (18c) toward the
receiver (17) to flow. The relief valve (117) automatically opens
when the refrigerant pressure working thereon becomes a
predetermined pressure (1.5 MPa, for example) while on the other
hand maintaining the state in which the liquid branch pipe (66) is
closed until it exceeds the predetermined pressure. The liquid
branch pipe (66) is connected at one end thereof between the check
valve (CV5) and the receiver (17) and is connected at the other end
thereof between the closing valve (18c) and a connection point of
the outdoor liquid pipe (62) to the auxiliary liquid pipe (65)
which is located on the closing valve (18c) side.
[0101] In the outdoor liquid pipe (62), a check valve (CV7) is
provided in the first outflow pipe (63b) between a connection point
to the auxiliary liquid pipe (65) which is located on the closing
valve (18c) side and a connection point to the liquid branch pipe
(66) which is located on the closing valve (18c) side. The check
valve (CV7) allows only the refrigerant flowing from the receiver
(17) toward the closing valve (18c) to flow. Between the receiver
(17) and the check valve (CV5) in the outdoor liquid pipe (62), one
end of a hot gas bypass pipe (71) as an introduction pipe is
connected. The hot gas bypass pipe (71) is connected at the other
end thereof between the closing valve (18b) of the outdoor second
gas pipe (58b) and the first four-way switching valve (12), and a
solenoid valve (SV1) is provided in the middle thereof. The hot gas
bypass pipe (71) and the solenoid valve (SV1) compose a refrigerant
return mechanism (5) in the present invention.
[0102] To the liquid branch pipe (66), a liquid injection pipe (67)
is connected of which one end is connected to a connection part
between the suction pipe (61a) and the low-reassure gas pipe (64).
The other end of the injection pipe (67) is connected between the
check valve (CV6) and the relief valve (117). The liquid injection
pipe (67) is provided with a motor-operated expansion valve (67a)
for flow rate adjustment.
[0103] <Indoor Unit>
[0104] The indoor unit (20) includes an indoor heat exchanger (an
air conditioning heat exchanger) (21) as a second user side heat
exchanger and an indoor expansion valve (22) as an expansion
mechanism. On the gas side of the indoor heat exchanger (21), the
second gas side communication pipe (52) is connected. On the other
hand, on the liquid side thereof, the second branch liquid pipe
(55) of the liquid side communication pipes (53, 54, 55) is
connected via the indoor expansion valve (22). The indoor heat
exchanger (21) is a fin and tube heat exchanger of cross fin type,
for example, and an indoor fan (23) as a user side fan is provided
in the vicinity thereof. The indoor expansion valve (22) is a
motor-operated expansion valve.
[0105] <Refrigerating Unit>
[0106] The refrigerating unit (30) includes a refrigerating heat
exchanger (31) as a first user side heat exchanger and a
refrigerating expansion valve (32) as an expansion mechanism. On
the liquid side of the refrigerating heat exchanger (31), the first
branch liquid pipe (54) (the refrigerating side first branch liquid
pipe (54a)) of the liquid side communication pipes (53, 54, 55) is
connected via a solenoid valve (SV2) and the refrigerating
expansion valve (32). The solenoid valve (SV2) is used for stopping
refrigerant flow in a thermo-off operation (operation stop). On the
other hand, the refrigerating heat exchanger (31) is connected on
the gas side thereof to a refrigerating side branch gas pipe (51a)
branching from the first gas side communication pipe (51).
[0107] The refrigerating heat exchanger (31) communicates with the
suction side of the inverter compressor (11A), and the indoor heat
exchanger (21) communicates with the suction side of the second
non-inverter compressor (11C) in a cooling operation. The
refrigerant pressure (evaporation pressure) in the refrigerating
heat exchanger (31) is lower than the refrigerant pressure
(evaporation pressure) in the indoor heat exchanger (21).
Specifically, the refrigerant evaporation temperature in the
refrigerating heat exchanger (31) is -10.degree. C., for example,
while the refrigerant evaporation temperature in the indoor heat
exchanger (21) is +5.degree. C., for example so that the
refrigerant circuit (50) serves as a plural-evaporation-temperature
circuit.
[0108] The refrigerating expansion valve (32) is a temperature
sensing expansion valve and includes a temperature sensing cylinder
mounted on the gas side of the refrigerating heat exchanger (31).
Accordingly, the opening of the refrigerating expansion valve (32)
is adjusted on the basis of the temperature of the refrigerant at
the outlet of the refrigerating heat exchanger (31). The
refrigerating heat exchanger (31) is a fin and tube heat exchanger
of cross fin type, and a refrigerating fan (33) as a cooling fan is
provided in the vicinity thereof.
[0109] <Freezing Unit>
[0110] The freezing unit (40) includes a freezing heat exchanger
(41) as a first user side heat exchanger, a freezing expansion
valve (424) as an expansion mechanism, and a booster compressor
(43) as a freezing compressor. The liquid side of the freezing heat
exchanger (41) is connected to the first branch liquid pipe (54)
(the freezing side first branch liquid pipe (54b)) of the liquid
side communication pipes (53, 54, 55) via a solenoid valve (SV3)
and the freezing expansion valve (42).
[0111] The gas side of the freezing heat exchanger (41) and the
suction side of the booster compressor (43) are connected to each
other by means of a connection gas pipe (68). The discharge side of
the booster compressor (43) is connected to a freezing side branch
gas pipe (51b) branching from the first gas side communication pipe
(51). The freezing side branch gas pipe (51b) is provided with a
check valve (CV8) and an oil separator (44). An oil return pipe
(69) including a capillary tube (45) is connected between the oil
separator (44) and the connection gas pipe (68).
[0112] The booster compressor (43) compresses the refrigerant in
two stages in combination with the first system compression
mechanism (11D) so that the refrigerant evaporation temperature in
the freezing heat exchanger (41) is lower than that in the
refrigerating heat exchanger (31). The refrigerant evaporation
temperature of the freezing heat exchanger (41) is set at
-35.degree. C., for example.
[0113] The freezing expansion valve (42) is a temperature sensing
expansion valve and includes a temperature sensing cylinder mounted
on the gas side of the refrigerating heat exchanger (31). The
freezing heat exchanger (41) is a fin and tube type heat exchanger
of cross fin type, for example, and a freezing fan (46) as a
cooling fan is provided in the vicinity thereof.
[0114] A bypass pipe (70) including a check valve (CV9) is
connected between the connection gas pipe (68) located on the
suction side of the booster compressor (43) and a part of the
freezing side branch gas pipe (51b) between the oil separator (44)
and the check valve (CV8). The bypass pipe (70) is so composed that
the refrigerant bypasses the booster compressor (43) when the
booster compressor (43) is sopped due to disorder or the like.
[0115] <Control System>
[0116] The refrigerant circuit (50) is provided with various kinds
of sensors and switches. The high-pressure gas pipe (57) of the
outdoor unit (10) is provided with a high-pressure pressure sensor
(75) for detecting the pressure of high-pressure refrigerant and a
discharge side temperature sensor (76) for detecting the
temperature of the high-pressure refrigerant. The discharge pipe
(56c) of the second non-inverter compressor (11C) is provided with
a discharge side temperature sensor (77) for detecting the
temperature of the high-pressure refrigerant. Pressure switches
(78) for high pressure protection which open when the pressure of
the high-pressure refrigerant becomes a predetermined value to stop
the corresponding compressors (11A, 11B, 11C) are provided at the
inverter compressor (11A), the first non-inverter compressor (11B),
and the second non-inverter compressor (11C).
[0117] In the suction pipes (61a, 61c) of the inverter compressor
(11A) and the second non-inverter compressor (11C), there are
provided respective low-pressure sensors (79, 80) for detecting the
pressure of low-pressure refrigerant and respective suction side
temperature sensors (81, 82) for detecting the temperature of the
low-pressure refrigerant. The low-pressure pressure sensor (79) and
the suction side temperature sensor (81) of the inverter compressor
(11A) compose suction side superheat detection means in the present
invention.
[0118] The outdoor heat exchanger (15) is provided with an outdoor
heat exchange sensor (83) for detecting the evaporation temperature
or the condensation temperature of the refrigerant as the
refrigerant temperature in the outdoor heat exchanger (15). The
outdoor unit (10) is provided with an outdoor air temperature
sensor (84) for detecting the outdoor air temperature.
[0119] The indoor heat exchanger (21) is provided with an indoor
heat exchange sensor (85) for detecting the condensation
temperature or the evaporation temperature of the refrigerant as
the refrigerant temperature in the indoor heat exchanger (21) and a
gas temperature sensor (86) on the gas side for detecting the
temperature of the gas refrigerant. The indoor unit (20) is
provided with a room temperature sensor (87) for detecting the
indoor air temperature.
[0120] The refrigerating unit (30) is provided with a refrigeration
temperature sensor (88) for detecting the inside temperature of the
refrigerated showcase. The freezing unit (40) is provided with a
freezing temperature sensor (89) for detecting the inside
temperature of the frozen showcase. On the discharge side of the
booster compressor (43), a pressure switch (90) for high pressure
protection is provided which opens when the pressure of the
discharged refrigerant becomes a predetermined value to stop the
compressor (43).
[0121] Output signals from each sensor and each switch are input to
a controller (95) as control means. The controller (95) controls
the operation of the refrigerant circuit (50) by switching eight
kinds of operation modes, which will be described later. The
controller (95) performs, in operation, control for activation,
stop, and capacity adjustment of the inverter compressor (11A),
control for activation and stop of the first non-inverter
compressor (11B) and the second non-inverter compressor (11C), and
control for opening adjustment of the outdoor expansion valve (19)
and the indoor expansion valve (22), and performs, in addition,
control for switching of each four-way switching valve (12, 13, 14)
and control for opening adjustment of the liquid injection pie (67)
and the motor-operated expansion valve (67a).
[0122] Further, the controller (95) controls opening/closing of the
solenoid valve (SV1) of the hot gas bypass pipe (71) in a first
heating/freezing operation, which will be described later.
Specifically, the following control is performed in the first
heating/freezing operation where a refrigerant circulation path is
formed in which the refrigerant sent out from the compression
mechanism (11D) flows from the indoor unit (20) as the second user
side unit to the refrigerating unit (30) and the freezing unit (40)
as the first user side units and is then returned to the
compression mechanism (11D).
[0123] First, the controller (95) detects the degree of superheat
of the refrigerant flowing from the refrigerating heat exchanger
(31) and the freezing heat exchanger (41) as the first user side
heat exchangers toward the suction side of the compression
mechanism (11D) with the use of the detection value of the
low-pressure pressure sensor (79) and the detection value of the
suction side temperature sensor (81). When the detected degree of
superheat is equal to or larger than a predetermined value, the
controller (95) opens the solenoid valve (SV1). Or, when the
detected degree thereof is smaller than a predetermined value, it
closes the solenoid valve (SV1).
[0124] The controller (95) judges from the degree of superheat of
the refrigerant sucked to the compression mechanism (11D) whether
or not the refrigerant is short in the refrigerating heat exchanger
(31) and the freezing heat exchanger (41) as the first user side
heat exchangers. When the controller (95) judges that the
refrigerant is short in the refrigerating heat exchanger (31) and
the freezing heat exchanger (41), the controller (95) opens the
solenoid valve (SV1) for returning the refrigerant in the receiver
(17) to the circulation path.
[0125] --Driving Operation--
[0126] Each driving operation that the refrigerating apparatus (1)
performs will be described next. In Embodiment 1, eight operation
modes can be set. Specifically, the apparatus (1) can be set to:
(i) a cooling operation for performing only cooling by the indoor
unit (20); (ii) a freezing operation for performing only cooling by
the refrigerating unit (30) and the freezing unit (40); (iii) a
first cooling/freezing operation for simultaneously performing
cooling by the indoor unit (20) and cooling by the refrigerating
unit (30) and the freezing unit (40); (iv) a second
cooling/freezing operation as an operation performed when the
cooling capacity of the indoor unit (20) is short in the first
cooling/freezing operation; (v) a heating operation for performing
only heating by the indoor unit (20); (vi) a first heating/freezing
operation for performing heating by the indoor unit (20) and
cooling by the refrigerating unit (30) and the freezing unit (40)
through a 100% heat recovery operation without using the outdoor
heat exchanger (15); (vii) a second heating/freezing operation
performed when the heating capacity of the indoor unit (20) is
surplus in the first heating/freezing operation; and (viii) a third
heating/freezing operation performed when the heating capacity of
the indoor unit (20) is short in the first heating/freezing
operation.
[0127] Each driving operation will be described below
specifically.
[0128] <Cooling Operation>
[0129] The cooling operation is an operation for performing only
cooling by the indoor unit (20). In the cooling operation, as shown
in FIG. 2, the inverter compressor (11A) serves as the first system
compressor mechanism (11D) while the first non-inverter compressor
(11B) and the second non-inverter compressor (11C) serve as the
second system compression mechanism (11B). Only the first
non-inverter compressor (11B) and the second non-inverter
compressor (11C) as the second system compression mechanism (11E)
are driven.
[0130] Further, as indicated by the solid lines in FIG. 2, the
first four-way switching valve (12) and the second four-way
switching valve (13) are switched to the first state while the
third four-way switching valve (14) is switched to the second
stated. All of the outdoor expansion valve (19), the motor-operated
expansion valve (67a) of the liquid injection pipe (67), the
solenoid valve (SV1) of the hot gas bypass pipe (71), the solenoid
valve (SV2) of the refrigerating unit (30), and the solenoid valve
(SV3) of the freezing unit (40) are closed.
[0131] In this state, the refrigerant discharged from the first
non-inverter compressor (11B) and the second non-inverter
compressor (11C) flows from the first four-way switching valve (12)
through the outdoor first gas pipe (58a) into the outdoor heat
exchanger (15) to be condensed. The thus condensed refrigerant
flows through the outdoor liquid pipe (62), the receiver (17), the
collection liquid pipe (53), and the second branch pipe (55) of the
liquid side communication pipes (53, 54, 55), and then flows via
the indoor expansion valve (22) into the indoor heat exchanger (21)
to be evaporated. The thus evaporated gas refrigerant flows from
the second gas side communication pipe (52) through the outdoor
second gas pipe (58b), the first four-way switching valve (12), and
the second four-way switching valve (13) into the suction pipe
(61c) of the second non-inverter compressor (11C). Part of this
low-pressure gas refrigerant is returned to the second non-inverter
compressor (11C). On the other hand, the other gas refrigerant
branches from the suction pipe (61c) of the second non-inverter
compressor (11C) into the branch pipe (61e) and flows via the third
four-way switching valve (14) to be returned to the first
non-inverter compressor (11B). Repetition of this refrigerant
circulation cools the inside of the store.
[0132] Under this driving operation, activation and stop of the
first non-inverter compressor (11B) and the second non-inverter
compressor (11C) and the opening of the indoor expansion valve (22)
and the like are controlled according to the indoor cooling load.
Only one of the compressors (11B, 11C) may be driven.
[0133] <Freezing Operation>
[0134] The freezing operation is an operation for performing only
cooling by the refrigerating unit (30) and the freezing unit (40).
In the freezing operation, as shown in FIG. 3, the inverter
compressor (11A) and the first non-inverter compressor (11B) serve
as the first system compression mechanism (11D) while the second
non-inverter compressor (11C) serves as the second system
compression mechanism (11E). The inverter compressor (11A) and the
first non-inverter compressor (11B) as the first system compression
mechanism (11D) are driven, and the booster compressor (43) is
driven in addition with the second non-inverter compressor (11C)
stopped.
[0135] The first four-way switching valve (12), the second four-way
switching valve (13), and the third four-way switching valve (14)
are switched to the first state, as indicated by the solid lines in
FIG. 3. Further, the solenoid valve (SV2) of the refrigerating unit
(30) and the solenoid valve (SV3) of the freezing unit (40) are
opened while the solenoid valve (SV1) of the hot gas bypass pipe
(71), the outdoor expansion valve (19), and the indoor expansion
valve (22) are closed. The motor-operated expansion valve (67a) of
the liquid injection pipe (67) is set to be closed fully or set at
a predetermined opening so as to allow the liquid refrigerant to
flow at a predetermined flow rate according to the driving
condition.
[0136] In this state, the refrigerant discharged from the inverter
compressor (11A) and the first non-inverter compressor (11B) flows
from the first four-way switching valve (12) through the outdoor
first gas pipe (58a) into the outdoor heat exchanger (15) to be
condensed. The thus condensed refrigerant flows through the outdoor
liquid pipe (62), the receiver (17), and the collection liquid pipe
(53) of the liquid side communication pipes (53, 54, 55) and then
branches into the refrigerating side first branch liquid pipe (54a)
and the freezing side first branch liquid pipe (54b).
[0137] The liquid refrigerant flowing in the refrigerating side
first branch liquid pipe (54a) flows via the refrigerating
expansion valve (32) into the refrigerating heat exchanger (31) to
be evaporated and then flows into the refrigerating side branch gas
pipe (51a). On the other hand, the refrigerant flowing in the
freezing side first branch liquid pipe (54b) flows via the freezing
expansion valve (42) into the freezing heat exchanger (41) to be
evaporated. The gas refrigerant thus evaporated in the freezing
heat exchanger (41) is sucked into and compressed in the booster
compressor (43) and is then discharged to the freezing side branch
gas pipe (51b).
[0138] The gas refrigerant evaporated in the refrigerating heat
exchanger (31) and the gas refrigerant discharged from the booster
compressor (43) interflow in the first gas side communication pipe
(51), flow through the low-pressure gas pipe (64), and is then
returned to the inverter compressor (11A) and the first
non-inverter compressor (11B). Repetition of the above refrigerant
circulation cools each inside of the refrigerated showcase and the
frozen showcase.
[0139] The pressure of the refrigerant in the freezing heat
exchanger (41), which is sucked to the booster compressor (43), is
lower than the that in the refrigerating heat exchanger (31). As a
result, for example, the refrigerant temperature (evaporation
temperature) in the freezing heat exchanger (41) is -35.degree. C.
while the refrigerant temperature (evaporation temperature) in the
refrigerating heat exchanger (31) is -10.degree. C.
[0140] In the freezing operation, activation and stop of the first
non-inverter compressor (11B) and activation and stop or capacity
control of the inverter compressor (11A) are performed on the basis
of the low-pressure refrigerant pressure (LP) that the low-pressure
pressure sensor (79) detects to perform the operation according to
the freezing load.
[0141] For example, in order to perform control for increasing the
capacity of the compression mechanism (11D), the inverter
compressor (11A) is driven first with the first non-inverter
compressor (11B) stopped. When the load of the inverter compressor
(11A) is further increased after the load reaches the maximum
capacity, the first non-inverter compressor (11B) is driven and the
capacity of the inverter compressor (11A) is reduced to the minimum
capacity. When the load is further increased thereafter, the
capacity of the inverter compressor (11A) is increased with the
first non-inverter compressor (11B) driven. Control for decreasing
the capacities of the compressors are performed in the reverse
operation to this capacity increasing control.
[0142] Each opening of the refrigerating expansion valve (32) and
the freezing expansion valve (42) is under superheat control by a
temperature sensitive cylinder. This is applied to each of the
following operations.
[0143] <First Cooling/Freezing Operation>
[0144] The first cooling/freezing operation is an operation for
simultaneously performing cooling by the indoor unit (20) and
cooling by the refrigerating unit (30) and the freezing unit (40).
In the first cooling/freezing operation, as shown in FIG. 4, the
inverter compressor (11A) and the first non-inverter compressor
(11B) serve as the first system compression mechanism (11D) while
the second non-inverter compressor (11C) serves as the second
system compression mechanism (11E). The inverter compressor (11A),
the first non-inverter compressor (11B), and the second
non-inverter compressor (11C) are driven, and the booster
compressor (43) is driven in addition.
[0145] The first four-way switching valve (12), the second four-way
switching valve (13), and the third four-way switching valve (14)
are switched to the first state, as indicated by the solid lines in
FIG. 4. The solenoid valve (SV2) of the refrigerating unit (30) and
the solenoid valve (SV3) of the freezing unit (40) are opened while
the solenoid valve (SV1) of the hot gas bypass pipe (71) and the
outdoor expansion valve (19) are closed. The motor-operated
expansion valve (67a) of the liquid injection pipe (67) is set to
be closed fully or set at a predetermined opening so as to allow
the liquid refrigerant to flow at a predetermined flow rate to the
suction side of the compression mechanism (11D) according to the
driving condition.
[0146] In this state, the refrigerant discharged from the inverter
compressor (11A), the first non-inverter compressor (11B), and the
second non-inverter compressor (11C) interflows in the
high-pressure gas pipe (57), flows from the first four-way
switching valve (12) through the outdoor first has pipe (58a) into
the outdoor heat exchanger (15) to be condensed. The thus condensed
refrigerant flows through the outdoor liquid pipe (62) and the
receiver (17) into the collection liquid pipe (53) of the liquid
side communication pipes (53, 54, 55).
[0147] Part of the liquid refrigerant flowing in the collection
liquid pipe (53) of the liquid side communication pipes (53, 54,
55) branches into the second branch liquid pipe (55) and flows via
the indoor expansion valve (22) into the indoor heat exchanger (21)
to be evaporated. The thus evaporated gas refrigerant flows from
the second gas side communication pipe (52) through the outdoor
second gas pipe (58b), the first four-way switching valve (12), and
the second four-way switching valve (13) into the suction pipe
(61c) and is then returned to the second non-inverter compressor
(11C).
[0148] On the other hand, the liquid refrigerant flowing in the
collection liquid pipe (53) of the liquid side communication pipes
(53, 54, 55) branches into the refrigerating side first branch
liquid pipe (54a) and the freezing side first branch liquid pipe
(54b). The liquid refrigerant flowing in the refrigerating side
first branch liquid pipe (54a) flows via the refrigerating
expansion valve (32) into the refrigerating heat exchanger (31) to
be evaporated and then flows into the refrigerating side branch gas
pipe (51a). The liquid refrigerant flowing in the freezing side
first branch liquid pipe (54b) flows via the freezing expansion
valve (42) into the freezing heat exchanger (41) to be evaporated.
The gas refrigerant thus evaporated in the freezing heat exchanger
(41) is sucked into and compressed in the booster compressor (43)
and is then discharged to the freezing side branch gas pipe
(51b).
[0149] The gas refrigerant evaporated in the refrigerating heat
exchanger (31) and the gas refrigerant discharged from the booster
compressor (43) interflow in the first gas side communication pipe
(51), flows through the low-pressure gas pipe (64), and is then
returned to the inverter compressor (11A) and the first
non-inverter compressor (11B). Repetition of the above refrigerant
circulation cools the inside of the store and cools each inside of
the refrigerated showcase and the frozen showcase.
[0150] <Second Cooling/Freezing Operation>
[0151] The second cooling/freezing operation is an operation
performed in the case where the cooling capacity of the indoor unit
(20) is short in the first cooing/freezing operation and an
operation in which the first non-inverter compressor (11B) is
switched for air conditioning. The state in the second
cooling/freezing operation is basically the same as that in the
first cooling/freezing operation, as shown in FIG. 5, wherein the
third four-way switching valve (14) is switched to the second state
dislike the first cooling/freezing operation.
[0152] Accordingly, in the second cooling/freezing operation, the
refrigerant discharged from the inverter compressor (11A), the
first non-inverter compressor (11B), and the second non-inverter
compressor (11C) is condensed in the outdoor heat exchanger (15)
while being evaporated in the indoor heat exchanger (21), the
refrigerating heat exchanger (31), and the freezing heat exchanger
(41), similarly to that in the first cooling/freezing
operation.
[0153] Then, the refrigerant evaporated in the indoor heat
exchanger (21) is returned to the first non-inverter compressor
(11B) and the second non-inverter compressor (11C) while the
refrigerant evaporated in the refrigerating heat exchanger (31) and
the freezing heat exchanger (41) is returned to the inverter
compressor (11A). With the use of the two compressors (11B, 11C)
for air conditioning, the shortage of the cooling capacity is
supplemented.
[0154] <Heating Operation>
[0155] The heating operation is an operation for performing only
heating by the indoor unit (20). In the heating operation, as shown
in FIG. 6, the inverter compressor (11A) serves as the first system
compression mechanism (11D) while the first non-inverter compressor
(11B) and the second non-inverter compressor (11C) serve as the
second system compression mechanism (11E). Only the first
non-inverter compressor (11B) and the second non-inverter
compressor (11C) as the second system compression mechanism (11E)
are driven.
[0156] Further, as indicated by the solid lines in FIG. 6, the
first four-way switching valve (12) is switched to the second
state, the second four-way switching valve (13) is switched to the
first state, and third four-way switching valve (14) is switched to
the second state. The motor-operated expansion valve (67a) of the
liquid injection pipe (67), the solenoid valve (SV1) of the hot gas
bypass pipe (71), the solenoid valve (SV2) of the refrigerating
unit (30), and the solenoid valve (SV3) of the freezing unit (40)
are closed. The indoor expansion valve (22) is opened fully while
the outdoor expansion valve (19) is controlled to be opened at a
predetermined opening.
[0157] In this state, the refrigerant discharged from the first
non-inverter compressor (11B) and the second non-inverter
compressor (11C) flows from the first four-way switching valve (12)
through the outdoor second gas pipe (58b) and the second gas side
communication pipe (52) into the indoor heat exchanger (21) to be
condensed. The thus condensed liquid refrigerant flows from the
second branch liquid pipe (55) of the liquid side communication
pipes (53, 54, 55) into the collection liquid pipe (53), passes
through the liquid branch pipe (66), and then flows into the
receiver (17). Thereafter, the liquid refrigerant flows via the
outdoor expansion valve (19) of the auxiliary liquid pipe (65) into
the outdoor heat exchanger (15) to be evaporated. The thus
evaporated gas refrigerant flows from the outdoor first gas pipe
(58a) via the first four-way switching valve (12) and the second
four-way switching valve (13) into the suction pipe (61c) of the
second non-inverter compressor (11C) and is then returned to the
first non-inverter compressor (11B) and the second non-inverter
compressor (11C). Repetition of the above refrigerant circulation
heats indoors.
[0158] Similarly to the cooling operation, the above operation can
be performed by only one compressor (11B, 11C).
[0159] <First Heating/Freezing Operation>
[0160] The first heating/freezing operation is a 100% heat recovery
operation for performing heating by the indoor unit (20) and
cooling by the refrigerating unit (30) and the freezing unit (40)
without using the outdoor heat exchanger (15). In the first
heating/freezing operation, as shown in FIG. 7, the inverter
compressor (11A) and the first non-inverter compressor (11B) serve
as the first system compression mechanism (11D) while the second
non-inverter compressor (11C) serves as the second system
compression mechanism (11E). The inverter compressor (11A) and the
first non-inverter compressor (11B) are driven, and the booster
compressor (43) is driven in addition with the second non-inverter
compressor (11C) stopped.
[0161] Further, as indicated by the solid lines in FIG. 7, the
first four-way switching valve (12) is switched to the second state
while the second four-way switching valve (13) and the third
four-way switching valve (14) are switched to the first state. The
solenoid valve (SV2) of the refrigerating unit (30) and the
solenoid valve (SV3) of the freezing unit (40) are opened while the
outdoor expansion valve (19) is closed. Opening/closing of the
solenoid valve (SV1) of the hot gas bypass pipe (71) is controlled
on the basis of the degree of superheat of the refrigerant flowing
in the suction pipe (61a) which is detected from the detection
value of the low-pressure pressure sensor (79) and the detection
value of the suction side temperature sensor (81). Opening/closing
of the motor-operated expansion valve (67a) of the liquid injection
pipe (67) is controlled on the basis of the above degree of
superheat and the detection value of the discharge side temperature
sensor (76).
[0162] In this state, the refrigerant discharged from the inverter
compressor (11A) and the first non-inverter compressor (11B) flows
from the first four-way switching valve (12) through the outdoor
second gas pipe (58b) and the second gas side communication pipe
(52) into the indoor heat exchanger (21) to be condensed. The thus
condensed liquid refrigerant flows from the second branch liquid
pipe (55) of the liquid side communication pipe (53, 54, 55) and
branches into the refrigerating side first branch liquid pipe (54a)
and the freezing side first branch liquid pipe (54b) at a point
before the collection liquid pipe (53).
[0163] The liquid refrigerant flowing in the refrigerating side
first branch liquid pipe (54a) flows via the refrigerating
expansion valve (32) into the refrigerating heat exchanger (31) to
be evaporated and then flows into the refrigerating side branch gas
pipe (51a). On the other hand, the liquid refrigerant flowing in
the freezing side first branch liquid pipe (54b) flows via the
freezing expansion valve (42) into the freezing heat exchanger (41)
to be evaporated. The gas refrigerant thus evaporated in the
freezing heat exchanger (41) is sucked into and compressed in the
booster compressor (43) and is then discharged to the freezing side
branch gas pipe (51b).
[0164] The gas refrigerant evaporated in the refrigerating heat
exchanger (31) and the gas refrigerant discharged from the booster
compressor (43) interflow in the first gas side communication pipe
(51), flow through the low-pressure gas pipe (64), and is then
returned to the inverter compressor (11A) and the first
non-inverter compressor (11B). Repetition of the above refrigerant
circulation heats the inside of the store while cooling each inside
of the refrigerated showcase and the frozen showcase. During the
first heating/freezing operation, the 100% heat recovery is
performed in such a manner that the cooling capacities (evaporation
heat) of the refrigerating unit (30) and the freezing unit (40)
balance the heating capacity (condensation heat) of the indoor unit
(20). In this first heating/freezing operation, the refrigerant
circulation path is formed in which the refrigerant sent out from
the compression mechanisms (11D) flows from the indoor unit (20) to
the refrigerating unit (30) and the freezing unit (40) and is then
returned to the compression mechanism (11D). In this circulation
path, the refrigerant condensed in the indoor unit (20) flows
directly into the refrigerating unit (30) and the freezing unit
(40) without being returned to the outdoor unit (10).
[0165] During the first heating/freezing operation, the relief
valve (117) is closed. In so doing, the pressure in the liquid side
communication pipes (53, 54, 55) may be increased so high that the
refrigerant pressure working on the relieve valve (117) exceeds a
predetermined pressure (1.5 MPa, for example) to open the relief
valve (117). Even if the relief valve (117) is closed, refrigerant
leakage may occur. In these cases, the refrigerant in the
circulation path flows from the collection liquid pipe (53) through
the liquid branch pipe (66) into the receiver (17) to decrease the
refrigerant in the circulation path. When the refrigerant in the
circulation path is decreased, the flow rate of the refrigerant
decreases gradually in the refrigerating heat exchanger (31) and
the freezing heat exchanger (41), so that the region where the
refrigerant in a liquid-vapor two-phase state flows decreases while
the region where the single-phase gas refrigerant flows increases.
Hence, the degree of superheat of the refrigerant flowing out from
the refrigerating heat exchanger (31) and the freezing heat
exchanger (41) toward the compression mechanism (11D) increases
gradually.
[0166] The controller (95) opens the solenoid valve (SV1) when the
degree of superheat of the refrigerant flowing in the suction pipe
(61a) which is detected on the basis of the detection value of the
low-pressure pressure sensor (79) and the detection value of the
suction side temperature sensor (81) is equal to or larger than a
predetermined value. When the solenoid valve (SV1) is opened, the
high-pressure gas refrigerant discharged from the compression
mechanism (11D) is introduced into the receiver (17) through the
hot gas bypass pipe (71), as shown in FIG. 8, to increase the inner
pressure of the receiver (17). This pushes out the liquid
refrigerant in the receiver (17) forcedly to return the liquid
refrigerant to the circulation path through the collection liquid
pipe (53). The gas refrigerant is supplied from the circulation
path to the receiver (17), from which the liquid refrigerant is
pushed out. As a result, the refrigerant in the receiver (17)
decreases while the refrigerant in the circulation path increases.
This prevents refrigerant shortage in the refrigerating unit (30)
and the freezing unit (40) to avoid lowering of the cooling
capacities of the refrigerating unit (30) and the freezing unit
(40).
[0167] Further, when the liquid refrigerant in the receiver (17) is
returned to the circulation path to increase the refrigerant in the
circulation path, the degree of superheat of the refrigerant
flowing in the suction pipe (61a) decreases gradually. The
controller (95) closes the solenoid valve (SB1) when the degree of
superheat of the refrigerant which is detected on the basis of the
detection value of the low-pressure pressure sensor (79) and the
detection value of the suction side temperature sensor (81) is
lower than a predetermined value.
[0168] Second Heating/Freezing Operation
[0169] The second cooling/freezing operation is an operation
performed when the heating capacity of the indoor unit (20) is
surplus in the first heating/freezing operation. In the second
heating/freezing operation, as shown in FIG. 9, the inverter
compressor (11A) and the first non-inverter compressor (11B) serve
as the first system compression mechanism (11D) while the second
non-inverter compressor (11C) serves as the second system
compression mechanism (11E). The inverter compressor (11A) and the
first non-inverter compressor (11B) are driven, and the booster
compressor (43) is driven in addition with the second non-inverter
compressor (11C) stopped.
[0170] The second heating/freezing operation is the same as the
first heating/freezing operation in setting of the valves and the
like except that the second four-way switching valve (13A) is
switched to the second state, as indicated by the solid lines in
FIG. 9.
[0171] Accordingly, part of the refrigerant discharged from the
inverter compressor (11A) and the first non-inverter compressor
(11B) flows into the indoor heat exchanger (21) to be condensed,
similarly to that in the first heating/freezing operation. The thus
condensed liquid refrigerant flows from the second branch liquid
pipe (55) of the liquid side communication pipes (53, 54, 55) into
the first branch liquid pipe (54) (the refrigerating side first
branch liquid pipe (54a) and the freezing side first branch liquid
pipe (54)) at a point before the collection liquid pipe (53).
[0172] On the other hand, the other refrigerant discharged from the
inverter compressor (11A) and the first non-inverter compressor
(11B) flows from the auxiliary gas pipe (59) via the second
four-way switching valve (13) and the first four-way switching
valve (12) to the outdoor first gas pipe (58a) and flows into the
outdoor heat exchanger (15) to be condensed. The thus condensed
liquid refrigerant passes through the receiver (17) when flowing
into the outdoor liquid pipe (62), flows through the collection
liquid pipe (62) of the liquid side communication pipes (51, 54,
55) into the first branch liquid pipe (54) (the refrigerating side
first branch liquid pipe (54a) and the freezing side first branch
liquid pipe (54b)), and then interflows with the refrigerant from
the second branch liquid pipe (55).
[0173] Thereafter, the liquid refrigerant flowing in the
refrigerating side first branch liquid pipe (54a) flows into the
refrigerating heat exchanger (31) to be evaporated and then flows
into the refrigerating side branch gas pipe (Sla). The liquid
refrigerant flowing in the freezing side first branch liquid pipe
(54b) flows into the freezing heat exchanger (41) to be evaporated,
is sucked into and compressed in the booster compressor (43), and
is then discharged to the freezing side branch gas pipe (51b). The
gas refrigerant evaporated in the refrigerating heat exchanger (31)
and the gas refrigerant discharged from the booster compressor (43)
interflow in the first gas side communication pipe (51), flows
through the low-pressure gas pipe (64), and is then returned to the
inverter compressor (11A) and the first non-inverter compressor
(11B).
[0174] In the second heating/freezing operation, repetition of the
above refrigerant circulation heats the inside of the store while
cooling each inside of the refrigerated showcase and the frozen
showcase. In this operation, the cooling capacities (evaporation
heat) of the refrigerating unit (30) and the freezing unit (40) do
not balance the heating capacity (condensation heat) of the indoor
unit (20), so that the surplus condensation heat is released
outdoors in the outdoor heat exchanger (15).
[0175] <Third Heating/Freezing Operation>
[0176] The third heating/freezing operation is an operation
performed when the heating capacity of the indoor unit (20) is
short in the first heating/freezing operation. In the third
heating/freezing operation, as shown in FIG. 10, the inverter
compressor (11A) and the first non-inverter compressor (11B) serve
as the first system compression mechanism (11D) while the second
non-inverter compressor (11C) serves as the second system
compression mechanism (11E). The inverter compressor (11A), the
first non-inverter compressor (11B), and the second non-inverter
compressor (11C) are driven, and the booster compressor (43) is
driven in addition.
[0177] The third heating/freezing operation is the same in setting
as the first heating/freezing operation except that: the opening of
the outdoor expansion valve (19) is controlled; the solenoid valve
(SV1) is closed under no opening/closing control; and the second
non-inverter compressor (11C) is driven.
[0178] Accordingly, the refrigerant discharged from the inverter
compressor (11A), the first non-inverter compressor (11B), and the
second non-inverter compressor (11C) flows through the second gas
side communication pipe (52) into the indoor heat exchanger (21) to
be condensed, similarly to that in the first heating/freezing
operation. The thus condensed liquid refrigerant branches from the
second branch liquid pipe (55) of the liquid side communication
pipes (53, 54, 55) into the first branch liquid pipe (54) (the
refrigerating side first branch liquid pipe (54a) and the freezing
side first branch liquid pipe (54b)) and the collection liquid pipe
(53).
[0179] The liquid refrigerant flowing in the refrigerating side
first branch liquid pipe (54a) flows into the refrigerating heat
exchanger (31) to be evaporated and then flows into the
refrigerating side branch gas pipe (51a). The refrigerant flowing
in the freezing side first branch liquid pipe (54b) flows into the
freezing heat exchanger (41) to be evaporated, is sucked into and
compressed in the booster compressor (43), and is then discharged
to the freezing side branch gas pipe (51b). The gas refrigerant
evaporated in the refrigerating heat exchanger (31) and the gas
refrigerant discharged from the booster compressor (43) interflow
in the first gas side communication pipe (51), flow through the
low-pressure gas pipe (64), and are then returned to the inverter
compressor (11A) and the first non-inverter compressor (11B).
[0180] On the other hand, the liquid refrigerant having condensed
in the indoor heat exchanger (21) and flowing in the collection
liquid pipe (53) flows through the liquid branch pipe (66) into the
receiver (17) and then flows via the outdoor expansion valve (19)
into the outdoor heat exchanger (15) to be evaporated. The thus
evaporated gas refrigerant flows into the outdoor first gas pipe
(58a), flows via the first four-way switching valve (12) and the
second four-way switching valve (13) into the suction pipe (61c) of
the second non-inverter compressor (11C), and is then returned to
the second non-inverter compressor (11C).
[0181] In the third heating/freezing operation, repetition of the
above refrigerant circulation heats the inside of the store while
cooling each inside of the refrigerated showcase and the frozen
showcase. In this operation, the cooling capacities (evaporation
heat) of the refrigerating unit (30) and the freezing unit (40) do
not balance the heating capacity (condensation heat) of the indoor
unit (20), so that the short evaporation heat is obtained from the
outdoor heat exchanger (15).
[0182] --Effects of Embodiment 1--
[0183] In Embodiment 1, in the first heating/freezing operation in
which the circulation path of which the refrigerant decreases when
the refrigerant flows into the receiver (17) is formed, the
solenoid valve (SV1) of the hot gas bypass pipe (71) is opened to
return the liquid refrigerant in the receiver (17) to the
circulation path. When the liquid refrigerant in the receiver (17)
is returned to the circulation path, the refrigerant flowing in the
indoor unit (20), the refrigerating unit (30), and the freezing
unit (40) as the user side units increases. Namely, the liquid
refrigerant in the receiver (17) is returned to the circulation
path by the refrigerant return mechanism (5) before the refrigerant
is short in the user side units (20, 30 40), thereby preventing the
refrigerant in the user side units (20, 30, 40) from being
short.
[0184] In addition, in Embodiment 1, in view of the fact that
whether or not the refrigerant in the refrigerating unit (30) and
the freezing unit (40) is short can be judged from the degree of
superheat of the refrigerant flowing from the refrigerating heat
exchanger (31) and the freezing heat exchanger (41) toward the
suction side of compression mechanism (11D), the solenoid valve
(SV1) of the hot gas bypass pipe (71) is controlled on the basis of
the detection value of the low-pressure pressure sensor (79) and
the detection value of the suction side temperature sensor (81).
Accordingly, the liquid refrigerant in the receiver (17) can be
returned to the circulation path at an appropriate timing before
the refrigerant is short in the refrigerating unit (30) and the
freezing unit (40). This prevents the cooling capacities of the
refrigerating unit (30) and the freezing unit (4) from lowering
definitely.
Embodiment 2 of the Invention
[0185] Embodiment 2 of the present invention will be described.
FIG. 11 is a diagram showing a refrigerant circuit of a
refrigerating apparatus (1) in accordance with Embodiment 2. The
refrigerating apparatus (1) of Embodiment 2 is different from that
of Embodiment 1 in the point that neither the hot gas bypass pipe
(71) nor the solenoid valve (SV1) is provided, wherein the second
four-way switching valve (13) as a communication mechanism serves
as the refrigerant return mechanism (5).
[0186] Description will given to an operation for returning the
liquid refrigerant in the receiver (17) to the circulation path in
the first heating/freezing operation. In the refrigerating
apparatus (1) of Embodiment 2, the controller (95) switches the
second four-way switching valve (13) to the second state when the
degree of superheat of the refrigerant flowing in the suction pipe
(61a) which is detected from the detection value of the
low-pressure pressure sensor (79) and the detection value of the
suction side temperature sensor (81) is equal to or larger than a
predetermined value.
[0187] When the second four-way switching valve (18) is set to the
second state, part of the high-pressure gas refrigerant discharged
from the compression mechanism (11D) flows from the auxiliary gas
pipe (59) via the second four-way switching valve (13) and the
first four-way switching valve (12) into the outdoor first has pipe
(58a) and further flows from the outdoor heat exchanger (15)
through the outdoor liquid pipe (62) into the receiver (17). During
this flow, the outdoor fan (16) remains being stopped. This
increases the inner pressure of the receiver (17), so that the
liquid refrigerant in the receiver (17) is pushed out forcedly to
be returned to the circulation path through the collection liquid
pipe (53).
[0188] It is noted that the state where the second four-way
switching valve (13) is set to the second state in the first
heating/freezing operation is the same as the state in the second
heating/freezing operation in Embodiment 1. Wherein, the second
heating/freezing operation in Embodiment 1 is performed for
lowering the heating capacity of the indoor unit (20) while on the
other hand the first heating/freezing operation in Embodiment 2 is
performed for forcedly returning the liquid refrigerant in the
receiver (17) to the circulation path. Further, the outdoor fan
(16) is driven for condensing the refrigerant in the outdoor heat
exchanger (15) in the second heating/freezing operation in
Embodiment 1. While on the other hand, the outdoor heat exchanger
(15) is only utilized as the flow path for introducing the
high-pressure gas refrigerant discharged from the compression
mechanism (11D) into the receiver (17) in the first
heating/freezing operation in Embodiment 2, and therefore, the
outdoor fan (16) is not driven because condensation of the
refrigerant leads to introduction of the liquid refrigerant into
the receiver (17) to cause the refrigerant in the receiver (17) to
less decrease.
[0189] In Embodiment 2, the outdoor heat exchanger (15) is utilized
as the flow path for introducing the high-pressure gas refrigerant
into the receiver (17) to return the liquid refrigerant in the
receiver (17) to the circulation path without providing an
additional communication path for connecting the receiver (17) to
the discharge side of the compression mechanism (11D). Thus, the
refrigerating apparatus is simplified.
Embodiment 3 of the Invention
[0190] Embodiment 3 of the present invention will be described.
FIG. 12 is a diagram showing a refrigerant circuit of a
refrigerating apparatus (1) in accordance with Embodiment 3. The
refrigerating apparatus (1) in accordance with Embodiment 3 is
different from that in accordance with Embodiment 1 in the point
that neither the hot gas bypass pipe (71) nor the solenoid valve
(SV1) is provide and the connection point of the liquid injection
pipe (67) is different from that in Embodiment 1.
[0191] The liquid injection pipe (67) is connected at one end
thereof to a connection point between the suction pipe (61a) and
the low-pressure gas pipe (64) and is connected at the other end
thereof between the receiver (17) and a connection point of the
outdoor liquid pipe (62) to the auxiliary liquid pipe (65) which is
located on the closing valve (18c) side. The liquid injection pipe
(67) is a communication pipe for allowing the receiver (17) to
communicate with the suction side of the compression mechanism
(11D) and composes the refrigerant return mechanism (5) in
combination with the motor-operated expansion valve (67a).
[0192] Description will be given to an operation for returning the
liquid refrigerant in the receiver (17) to the circulation path in
the first heating/freezing operation. In the refrigerating
apparatus (1) of Embodiment 3, the controller (95) opens the
motor-operated expansion valve (67a) when the degree of superheat
of the refrigerant flowing in the suction pipe (61a) which is
detected on the basis of the detection value of the low-pressure
pressure sensor (79) and the detection value of the suction side
temperature sensor (81) is equal to or larger than a predetermined
value. This allows the receiver (17) to communicate with the
suction side of the compression mechanism (11D), so that the
compression mechanism (11D) forcedly sucks up the liquid
refrigerant in the receiver (17) to return it to the circulation
path.
[0193] It is noted that in each refrigerating apparatus (1) of
Embodiment 1 and Embodiment 2, since the inner pressure of the
collection liquid pipe (53) is high even if the motor-operated
expansion valve (67a) is opened in the first heating/freezing
operation, the liquid refrigerant in the receiver (17) does not
flow out from the receiver (17).
[0194] In contrast, in Embodiment 3, the compression mechanism
(11D) sucks the liquid refrigerant in the receiver (17) when the
liquid refrigerant in the receiver (17) is returned to the
circulation path to lower the degree of superheat on the suction
side of the compression mechanism (11D). Accordingly, the
refrigerant is returned to the circulation path to prevent
refrigerant shortage, and the degree of superheat on the suction
side is suppressed to reduce the required input of the compression
mechanism (11D).
Other Embodiments
[0195] The above embodiments may have any of the following
constructions. In the above embodiments, the controller (95)
controls the refrigerant return mechanism (5) on the basis of the
detection value of the low-pressure pressure sensor (79) and the
detection value of the suction side temperature sensor (81), but
may control the refrigerant return mechanism (5) on the basis of
the detection values of the high-pressure pressure sensor (75) and
the discharge side temperature sensor (76). The controller (95)
performs an operation for returning the liquid refrigerant in the
receiver (17) to the circulation path when the degree of superheat
of the refrigerant discharged from the compression mechanism (11D)
which is calculated on the basis of the detection value of the
high-pressure pressure sensor (75) and the detection value of the
discharge side temperature sensor (76) is equal to or higher larger
than a predetermined value. The high-pressure pressure sensor (75)
and the discharge side temperature sensor (76) compose discharge
side superheat detection means.
[0196] Alternatively, the controller (95) may control the
refrigerant return mechanism (5) on the basis of the detection
value of the discharge side temperature sensor (76) that detects
the temperature of the refrigerant discharged from the compression
mechanism (11D). The controller (95) performs an operation for
returning the liquid refrigerant in the receiver (17) to the
circulation path when the detection value of the discharge side
temperature sensor (76) is equal to or larger than a predetermined
value. The discharge side temperature sensor (76) composes
discharge side refrigerant temperature detection means.
[0197] Or, the controller (95) may control the refrigerant return
mechanism (5) on the basis of the opening of the motor-operated
expansion valve (67a) of the liquid injection pipe (67). The
controller (95) performs an operation for returning the liquid
refrigerant in the receiver (17) to the circulation path when the
opening of the motor-operated expansion valve (67a) is equal to or
larger than a predetermined opening (400 pulses or larger in a case
using a 480-pulse motor-operated expansion valve, for example).
Further, the controller (95) terminates the operation for returning
the liquid refrigerant in the receiver (17) to the circulation path
when the opening of the motor-operated expansion valve (67a) is
equal to or smaller than a predetermined opening (350 pulses or
smaller in the case using the 480-pulse motor-operated expansion
valve, for example).
[0198] It is noted that the opening of the motor-operated expansion
valve (67a) is controlled on the basis of the detection value of
the discharge side temperature sensor (76) and the degree of
superheat of the refrigerant flowing in the suction pipe (61a)
which is detected from the detection value of the low-pressure
pressure sensor (79) and the detection value of the suction side
temperature sensor (81). For example, the controller (95) increases
the opening of the motor-operated expansion valve (67a) when either
one of two conditions is satisfied, for example: one condition is
that the detection value of the discharge side temperature sensor
(76) is equal to or larger than 90.degree. C., and the other
condition is that the degree of superheat of the refrigerant
flowing in the suction pipe (61a) is equal to or larger than
5.degree. C.
[0199] Alternatively, the controller (95) may control the return
mechanism (5) on the basis of the degrees of superheat of the
outlets of the refrigerating heat exchanger (31) and the freezing
heat exchanger (41) serving as evaporators. In this case, a
temperature sensor and a pressure sensor are provided at the
respective outlets of the refrigerating heat exchanger (31) and the
freezing heat exchanger (41) for detecting the respective degrees
of superheat. For example, the controller (95) performs an
operation for returning the liquid refrigerant in the receiver (17)
to the circulation path when the state where the degree of
superheat of the refrigerant at either one of the outlets of the
refrigerating heat exchanger (31) and the freezing heat exchanger
(41) is equal to or larger than 10.degree. C. continues for a
period longer than ten minutes. Further, the controller (95)
terminates the operation for returning the liquid refrigerant in
the receiver (17) to the circulation path when the state where the
degree of superheat of the refrigerant at the outlet of the
evaporator, of which state where the degree of superheat of the
refrigerant continues to be 10.degree. C. or higher for the period
longer than ten minutes, is equal to or lower than 7.degree. C.
continues for a period longer than one minute. The control of the
refrigerant return mechanism (5) is not necessarily performed on
the basis of the degree of superheat of the refrigerant at all of
the outlets of the evaporators of the refrigerating unit (30) and
the freezing unit (40) but is performed on the basis of the degree
of superheat of the refrigerant at only the outlet of an evaporator
of a unit in which the liquid refrigerant less flows (a unit
installed at a high position in level, for example).
[0200] Moreover, the controller (95) may control the refrigerant
return mechanism (5) on the basis of the detection value of the
high-pressure pressure sensor (75). The high-pressure pressure in
the refrigeration cycle varies depending on the temperature of the
indoor space in which the indoor unit (20) is installed.
Accordingly, in this case, the refrigerant return mechanism (5) is
controlled on the basis of the saturation temperature of the
pressure detected by the high-pressure pressure sensor (75). For
example, the controller (95) performs an operation for returning
the liquid refrigerant in the receiver (17) to the circulation path
when the state where the difference between the saturation
temperature and the temperature of the indoor space is equal to or
smaller than 15.degree. C. continues for a period longer than ten
minutes. Further, the controller (95) terminates the operation for
returning the liquid refrigerant in the receiver (17) to the
circulation path when the state where the temperature difference is
equal to or larger than 15.degree. C. continues for a period longer
than one minute.
[0201] Furthermore, the controller (95) may control the refrigerant
return mechanism (5) on the basis of the detection value of the
low-pressure pressure sensor (79). For example, the controller (95)
performs an operation for returning the liquid refrigerant in the
receiver (17) to the circulation path when the state where the
detection value of the low-pressure pressure sensor (79) is equal
to or lower than 0.15 MPa continues for a period longer than 10
minutes. Further, the controller (95) terminates the operation for
returning the liquid refrigerant in the receiver (17) to the
circulation path when the state where the detection value of the
low-pressure pressure sensor (79) is equal to or larger than 0.2
MPa continues for a period longer than one minute.
[0202] Alternatively, the controller (95) may control the
refrigerant return mechanism (5) on the basis of some of conditions
of: the degree of superheat of the refrigerant flowing from the
refrigerating heat exchanger (31) and the freezing heat exchanger
(41) toward the suction side of the compression mechanism (11D);
the degree of superheat of the refrigerant discharged from the
compression mechanism (11D); the temperature of the refrigerant
discharged from the compression mechanism (11D); the opening of the
motor-operated expansion valve (67a) of the liquid injection pipe
(67); the degree of superheat of the refrigerant at the outlet of
an evaporator; the detection value of the high-pressure pressure
sensor (75); and the detection value of the low-pressure pressure
sensor (79). In this case, the controller (95) performs an
operation for returning the liquid refrigerant in the receiver (17)
to the circulation path when some of the conditions are
satisfied.
[0203] Alternatively, the controller (95) may perform an operation
for returning the liquid refrigerant in the receiver (17) to the
circulation path when the first heating/freezing operation for
performing the 100% heat recovery continues for 30 minutes or
longer. In the case where the outdoor air temperature is low
(-10.degree. C. or lower, for example), the inner pressure of the
receiver (17) becomes low, so that the liquid refrigerant is liable
to be retained. Accordingly, the refrigerant in the receiver (17)
may be returned to the circulation path when the first
heating/freezing operation continues for 20 minutes or longer.
[0204] Furthermore, the controller (95) may forcedly terminate the
operation for returning the liquid refrigerant in the receiver (17)
to the circulation path when the above operation continues for a
period longer than ten minutes.
[0205] In the above embodiments, the controller (95) may switch the
operation state by switching the first four-way switching valve
(12) as a switching mechanism to the second state temporarily when
much liquid refrigerant is retained in the receiver (17) in the
first heating/freezing operation (first operation mode). During
that time, the indoor expansion valve (22) is closed
simultaneously. The condition for switching the first four-way
switching valve (12) to the second state in this case is the same
as the condition when the refrigerant return mechanism (5) performs
the operation for returning the liquid refrigerant in the receiver
(17) to the circulation path. When the first four-way switching
valve (12) is set to the second state, the second operation mode is
set in which the refrigerant circulates in the same direction as
that in the freezing operation. Wherein, the outdoor fan (16)
remains stopped dislike the case of the freezing operation.
Accordingly, the high-pressure gas refrigerant discharged from the
compression mechanism (11D) flows through the outdoor heat
exchanger (15) into the receiver (17) to increase the inner
pressure of the receiver (17), so that the liquid refrigerant in
the receiver (17) is pushed out forcedly to be returned through the
collection liquid pipe (53) to the refrigerating unit (30) and the
freezing unit (40).
[0206] In the above embodiments, the liquid branch pipe (66) may be
provided with a solenoid valve rather than the relief valve
(117).
[0207] The above embodiments refer to the case where two indoor
units (20), eight refrigerating units (30), and one freezing unit
(40) are provided for one outdoor unit (10), but the numbers of the
user side units (20,30, 40) may be changed as far as the 100% heat
recovery operation is possible.
[0208] Further, the above embodiments refer to the case where the
compression mechanisms (11D, 11E) are composed of three compressors
(11A, 11B, 11C), but the number of the compressors may be changed
appropriately, as well.
[0209] It should be noted that the above embodiments are mere
essentially preferable examples and do not intend to limit the
scopes of the present invention, the applicable subjects, and the
use thereof.
INDUSTRIAL APPLICABILITY
[0210] As described above, the present invention is useful for
refrigerating apparatuses including a plurality of system user side
heat exchangers capable of performing a 100% heat recovery
operation therebetween.
* * * * *